I. Introduction

In the Philippines, many spouses ask whether a marriage can be annulled because one spouse committed infidelity, lived with another person, had an affair, abandoned the family, or started a new relationship while still married.

The direct answer is: infidelity and cohabitation, by themselves, are generally not independent grounds for annulment or declaration of nullity of marriage under Philippine law. They may, however, become legally relevant if they prove an existing ground recognized by law, especially psychological incapacity, fraud, violence or intimidation, sexual incapacity, or other circumstances affecting the validity of consent or the capacity to comply with essential marital obligations.

This distinction is critical. Philippine law does not treat every act of adultery, concubinage, cheating, abandonment, or cohabitation with a third person as a reason to erase a marriage. A spouse’s unfaithfulness may give rise to other legal remedies, such as criminal complaints, civil actions, legal separation, custody claims, support claims, protection orders, or property claims. But annulment and nullity cases require specific legal grounds.

II. Annulment, Declaration of Nullity, and Legal Separation: The Essential Distinction

Many people use the word “annulment” loosely to refer to any court process that ends a marriage. Philippine law, however, distinguishes among three major remedies.

A. Declaration of Nullity of Marriage

A declaration of nullity applies to a marriage that is considered void from the beginning. Legally, the marriage is treated as if it never validly existed, although a court judgment is still necessary for purposes such as remarriage, property settlement, custody, support, and civil registry annotation.

Common grounds include:

Absence of an essential or formal requirement of marriage;
Bigamous or polygamous marriage;
Incestuous or void marriages by reason of public policy;
Psychological incapacity under Article 36 of the Family Code;
Marriage solemnized by a person without authority, subject to legal nuances;
Certain marriages involving mistakes in identity.

In practice, many marital breakdown cases involving repeated infidelity are filed as petitions for declaration of nullity based on psychological incapacity, not as ordinary annulment cases.

B. Annulment of Voidable Marriage

Annulment applies to a marriage that was valid at the beginning but may be annulled because of a defect existing at the time of marriage.

Grounds generally include:

Lack of parental consent for a party aged eighteen to twenty-one at the time of marriage;
Insanity;
Fraud;
Force, intimidation, or undue influence;
Physical incapacity to consummate the marriage, if incurable;
Serious and incurable sexually transmissible disease existing at the time of marriage.

Annulment is different from nullity because the marriage is valid unless and until annulled by the court.

C. Legal Separation

Legal separation does not dissolve the marriage bond. The spouses remain married and cannot remarry. However, it allows separation of bed and board, separation of property, and certain consequences regarding custody, support, inheritance, and the guilty spouse’s rights.

Infidelity and cohabitation are often more directly relevant to legal separation than to annulment. Sexual infidelity, perversion, abandonment, and attempts against the life of the spouse may be grounds for legal separation, depending on the facts.

Thus, when the issue is simply that one spouse cheated or now lives with another person, the legally correct remedy may sometimes be legal separation, criminal action, or support/custody action—not annulment.

III. Is Infidelity a Ground for Annulment?

A. General Rule

Infidelity alone is not a ground for annulment of marriage in the Philippines.

A spouse may be unfaithful after marriage and still have entered into a valid marriage. The law does not automatically annul a marriage because one spouse later committed adultery, had an affair, maintained a mistress or lover, or lived with another person.

This is because annulment focuses on defects existing at or before the time of marriage, such as defective consent, incapacity, fraud, or physical incapacity. Infidelity that happens only after marriage usually shows marital misconduct, not necessarily invalidity of the marriage itself.

B. When Infidelity May Become Relevant

Infidelity may become relevant if it is evidence of a legally recognized ground, such as:

Psychological incapacity existing at the time of marriage;
Fraud, if the unfaithful conduct or condition existed before the marriage and was concealed in a legally significant way;
Force, intimidation, or undue influence, if the marriage was entered into under coercion;
Sexually transmissible disease, if existing at the time of marriage and concealed;
Bigamy, if the spouse was already married;
Lack of genuine consent, in rare factual situations;
Legal separation, where sexual infidelity is more directly relevant.

The important point is that infidelity must be connected to the legal ground. Courts do not annul marriages simply because one spouse is morally at fault.

IV. Is Cohabitation With Another Person a Ground for Annulment?

A. General Rule

Cohabitation by one spouse with another person is not, by itself, a ground for annulment.

A married person who lives with a lover, partner, mistress, paramour, or second family may be committing serious marital misconduct. But cohabitation after marriage does not automatically mean the marriage was void or voidable from the beginning.

B. Legal Relevance of Cohabitation

Cohabitation may become legally relevant in several ways:

As evidence of sexual infidelity;
As evidence of abandonment;
As evidence of psychological incapacity;
As proof in a possible criminal case for concubinage or related offenses;
As a basis for legal separation;
As a factor in child custody;
As a factor in support;
As a factor in property disputes;
As proof of bad faith in family relations;
As evidence of the breakdown of marital life.

However, it must still be tied to a recognized legal remedy.

V. Psychological Incapacity and Repeated Infidelity

A. Psychological Incapacity Under Article 36

Article 36 of the Family Code provides that a marriage is void if a spouse was psychologically incapacitated to comply with the essential marital obligations of marriage, even if such incapacity becomes manifest only after the marriage.

This is the most common legal theory used when infidelity is severe, repetitive, compulsive, long-standing, or connected to a spouse’s inability to assume marital obligations.

Psychological incapacity is not simply bad behavior. It is not mere refusal, neglect, immaturity, incompatibility, or marital difficulty. It refers to a condition that makes a spouse truly incapable of performing essential marital obligations.

B. Essential Marital Obligations

Essential marital obligations include:

Living together as husband and wife;
Observing mutual love, respect, and fidelity;
Rendering mutual help and support;
Caring for the family;
Supporting each other emotionally, financially, and morally;
Remaining faithful to the marital bond;
Respecting the dignity and security of the spouse;
Fulfilling responsibilities to children.

A spouse who repeatedly enters extramarital relationships may be violating the obligation of fidelity. But for psychological incapacity, the question is deeper: was the spouse psychologically incapable of fidelity and marital commitment from the beginning of the marriage?

C. Infidelity as Evidence, Not Automatic Ground

Infidelity may support psychological incapacity when it shows a persistent pattern, such as:

Habitual womanizing or repeated affairs;
Maintaining multiple partners;
Entering marriage without genuine capacity for exclusivity;
A long-standing pattern of deception and abandonment;
Compulsive sexual behavior;
Inability to form stable intimate commitment;
Disregard of spouse and children;
Repeated cohabitation with third parties;
Entering marriage while already emotionally or sexually committed elsewhere;
Refusal to recognize marital responsibilities;
Severe narcissistic, antisocial, dependent, or other dysfunctional patterns affecting marital obligations.

Still, evidence must show that the incapacity was not merely a later decision to cheat, but a condition existing at the time of marriage, though it may have become apparent only afterward.

D. Mere Sexual Affair Is Usually Insufficient

A single affair, a temporary lapse, or later falling in love with another person usually does not establish psychological incapacity. Courts look for proof of incapacity, not just moral failure.

The petitioner must show that the conduct reflects a deep-rooted inability to comply with marriage obligations, not merely deliberate refusal or ordinary marital misconduct.

VI. Fraud and Infidelity Before Marriage

Fraud is a ground for annulment only in specific situations recognized by law. Not every lie before marriage is legally sufficient.

A. Concealment of Pregnancy by Another Man

One recognized form of fraud is the concealment by the wife of the fact that she was pregnant by another man at the time of marriage.

This may be relevant where, before the wedding, the wife was already pregnant by someone else and concealed this fact from the husband. The law treats this concealment as a serious defect in consent.

B. Concealment of Sexually Transmissible Disease

Concealment of a sexually transmissible disease existing at the time of marriage may also be relevant, depending on the facts. If the disease is serious and incurable, it may also separately relate to annulment.

C. Prior Infidelity Not Always Fraud

If a spouse had a prior relationship, past sexual experience, or previous affair before the marriage, that alone does not automatically constitute fraud. The fraud must be of the kind recognized by law and must be material to consent.

For example, concealment of a prior boyfriend or girlfriend is generally different from concealment of pregnancy by another man, concealment of serious disease, or concealment of an existing marriage.

D. Infidelity Continuing Into Marriage

If a spouse was already in an ongoing relationship with another person at the time of marriage and merely used the marriage for convenience, immigration, money, family pressure, or appearance, this may support arguments regarding psychological incapacity, fraud, or lack of genuine marital intent depending on the evidence.

But again, the case must be framed under a recognized legal ground.

VII. Bigamy and Cohabitation

If a spouse is cohabiting with another person, it is important to determine whether there was another marriage.

A. Existing Prior Marriage

If one party was already validly married to someone else at the time of the later marriage, the later marriage is generally void for being bigamous, subject to specific legal exceptions and rules.

This is not ordinary annulment based on infidelity. It is a declaration of nullity because the second marriage was void from the beginning.

B. Subsequent Marriage While First Marriage Still Exists

If a spouse contracts another marriage while still married, this may expose that spouse to criminal liability for bigamy and may also affect the validity of the later marriage.

The first spouse may have remedies, but the proper action depends on which marriage is being questioned and on the facts surrounding any previous court declarations, presumptive death, or civil registry records.

C. Cohabitation Without Marriage

If the spouse merely lives with another person without marrying that person, that fact may support claims of infidelity, concubinage, legal separation, psychological incapacity, support, custody, or damages. But cohabitation alone does not make the original marriage void.

VIII. Legal Separation Based on Infidelity and Cohabitation

For many spouses, legal separation is the remedy most directly connected to infidelity.

A. Grounds Related to Infidelity

Legal separation may be based on sexual infidelity, perversion, abandonment, repeated physical violence, attempts to corrupt or induce a spouse or child into immoral conduct, drug addiction, habitual alcoholism, lesbianism or homosexuality existing after marriage, bigamous marriage, and other legally recognized grounds.

Sexual infidelity and cohabitation with another person may therefore be powerful grounds for legal separation.

B. Effects of Legal Separation

A decree of legal separation may result in:

Spouses being allowed to live separately;
Dissolution and liquidation of the property regime;
Forfeiture of the guilty spouse’s share in certain net profits, subject to legal rules;
Custody arrangements for children;
Support orders;
Disqualification of the guilty spouse from inheriting from the innocent spouse by intestate succession;
Revocation of certain donations or insurance designations, where allowed.

However, legal separation does not allow remarriage because the marriage bond remains.

C. Defenses in Legal Separation

A petition for legal separation may be denied where there is:

Condonation or forgiveness;
Consent to the offense;
Connivance;
Mutual guilt;
Collusion;
Prescription;
Reconciliation.

This is why timing and conduct after discovery of the affair can matter.

IX. Criminal Remedies: Adultery and Concubinage

Infidelity may also have criminal implications under the Revised Penal Code.

A. Adultery

Adultery may be committed by a married woman who has sexual intercourse with a man not her husband, and by the man who knows that she is married.

Each act of sexual intercourse may be treated as a separate offense.

B. Concubinage

Concubinage may be committed by a married man under specific circumstances, such as keeping a mistress in the conjugal dwelling, having sexual intercourse under scandalous circumstances with a woman not his wife, or cohabiting with her in another place.

Concubinage is more difficult to prove than adultery because the law defines it differently.

C. Who May File

Crimes against chastity generally require a complaint by the offended spouse and are subject to special rules. The offended spouse usually must include both guilty parties if both are alive, and there must be no consent or pardon.

D. Criminal Case Is Not Annulment

A criminal complaint for adultery or concubinage does not dissolve the marriage. It may punish the offender and establish civil liability, but it is not a substitute for annulment, nullity, or legal separation.

X. Civil Damages for Infidelity and Cohabitation

A spouse may, in some cases, seek damages based on Civil Code principles such as abuse of rights, acts contrary to morals, and injury to rights.

Possible civil claims may arise where the conduct is especially wrongful, humiliating, abusive, or damaging, such as:

Publicly maintaining a mistress or lover;
Abandoning the spouse and children;
Bringing the lover into the family home;
Using conjugal funds for the affair;
Defaming or humiliating the innocent spouse;
Exposing the family to scandal;
Causing emotional distress;
Committing violence or coercion connected with the affair.

Civil damages may include moral damages, actual damages, exemplary damages, and attorney’s fees, depending on proof and legal basis.

However, courts are careful in family disputes. The claimant must prove a legally actionable wrong and actual injury, not merely emotional pain from a failed marriage.

XI. Property Consequences of Infidelity and Cohabitation

Infidelity may affect property issues, especially where marital funds were used to support a third party or second family.

A. Use of Conjugal or Community Funds

If a spouse uses community or conjugal property to support a lover, maintain another household, buy property for a paramour, or finance a second family, the innocent spouse may have claims during liquidation or accounting.

Issues may include:

Recovery of diverted funds;
Reimbursement to the community or conjugal partnership;
Nullity of simulated transfers;
Fraudulent conveyances;
Donations to a lover;
Property registered in the name of a third party;
Support obligations to legitimate and illegitimate children.

B. Donations and Transfers to a Paramour

Donations between persons guilty of adultery or concubinage may be legally questionable. Transfers made to defeat the rights of the spouse or children may also be challenged.

C. Property Bought During Cohabitation With Another Person

If a married spouse buys property while cohabiting with a third person, determining ownership can be complex. The property may be presumed part of the marital property regime if acquired during marriage using marital funds, even if titled in another person’s name, subject to evidence.

XII. Child Custody, Support, and Infidelity

Infidelity does not automatically make a parent unfit. The controlling standard in custody disputes is the best interest of the child.

A. Custody

A spouse’s cohabitation with another person may matter if it affects the child’s welfare, safety, morality, emotional stability, schooling, or living conditions.

Relevant questions include:

Is the child exposed to conflict, abuse, neglect, or instability?
Does the new partner mistreat the child?
Is the home environment safe?
Is the parent still able to care for the child?
Is the child being used as leverage in the marital dispute?
Are there risks of violence or exploitation?

The court will not decide custody merely to punish a cheating spouse. The focus remains the child.

B. Support

Infidelity does not erase support obligations. A parent must support children according to law. A spouse may also be entitled to support depending on the circumstances and pending cases.

A spouse cannot refuse to support legitimate children because the other spouse committed infidelity. Likewise, children should not be punished for the marital misconduct of a parent.

C. Illegitimate Children From the Affair

If the affair produces a child, that child may have rights to support and inheritance from the biological parent. This may create financial issues affecting the legitimate family, but the law also protects illegitimate children.

XIII. Violence, Abuse, and Infidelity

Infidelity cases sometimes involve emotional abuse, economic abuse, threats, physical violence, stalking, harassment, or coercive control.

Where the victim is a woman or child, remedies may be available under laws protecting women and children from violence. Psychological violence, economic abuse, sexual violence, and physical violence may be relevant depending on the facts.

Examples include:

Threatening the spouse to accept the affair;
Depriving the wife and children of support;
Forcing the spouse out of the home;
Public humiliation;
Physical assaults after confrontation;
Harassment by the lover or third party;
Threats to take the children;
Controlling money to benefit the new partner;
Emotional abuse connected to the extramarital relationship.

Protection orders, criminal complaints, support orders, and custody remedies may be more urgent than annulment in these situations.

XIV. Evidence in Annulment or Nullity Cases Involving Infidelity

Evidence is crucial. Courts do not grant annulment or nullity based on bare accusations.

A. Evidence of Infidelity or Cohabitation

Possible evidence includes:

Photos;
Videos;
Messages;
Emails;
Social media posts;
Witness testimony;
Birth certificates of children from the affair;
Lease contracts;
Hotel records, if lawfully obtained;
Travel records;
Financial transfers;
Admissions;
Barangay blotter entries;
Police reports;
Private documents;
Public records;
School records showing the spouse as parent of another child;
Testimony of relatives, neighbors, or household workers.

Evidence must be legally obtained. Illegal access to phones, accounts, emails, or private communications can create legal problems.

B. Evidence of Psychological Incapacity

If the case is based on psychological incapacity, evidence may include:

The spouse’s history before marriage;
Pattern of relationships;
Family background;
Personality traits;
Repeated affairs;
Abandonment;
Statements showing inability to commit;
Expert psychological evaluation, where available;
Testimony of the petitioner;
Testimony of relatives and close friends;
Records showing long-standing dysfunctional behavior;
Attempts at reconciliation and failure;
Impact on spouse and children;
Proof that the incapacity existed at the time of marriage.

A psychological report can help, but the case does not stand on labels alone. The totality of evidence matters.

C. Evidence of Fraud

If the ground is fraud, evidence must show the specific fraudulent act, such as concealment of pregnancy by another man or other legally recognized fraud.

D. Evidence of Cohabitation

Cohabitation may be proven through:

Common residence;
Neighbors’ testimony;
Shared bills;
Public representation as partners;
Social media posts;
Children born from the relationship;
Documents listing the same address;
Financial support;
Household arrangements;
Admissions.

XV. Defenses Against an Annulment or Nullity Petition Based on Infidelity

A respondent may raise several defenses.

A. Infidelity Is Not a Ground

The respondent may argue that the petition is legally insufficient because it relies merely on adultery, concubinage, or cohabitation without establishing a recognized ground.

B. No Psychological Incapacity

In an Article 36 case, the respondent may argue that the acts show mere refusal, immorality, or marital misconduct, not psychological incapacity.

C. Infidelity Occurred Only After Marriage

If the alleged affair began long after the marriage and there was no proof of incapacity at the time of marriage, the petition may fail.

D. Isolated Misconduct

A single affair may be argued as insufficient to prove deep-rooted incapacity.

E. Collusion

The State is interested in preserving marriage. Courts must guard against collusion between spouses who simply agree to end their marriage by manufacturing grounds.

F. Insufficient Evidence

Unsupported accusations, hearsay, or illegally obtained evidence may be challenged.

G. Prescription in Voidable Marriage or Legal Separation Cases

Annulment of voidable marriages and legal separation actions are subject to time limits. A respondent may argue that the action was filed too late.

XVI. Procedure for Annulment or Declaration of Nullity

The process generally involves the filing of a verified petition in the proper Family Court.

A. Preparation

The petitioner usually prepares:

Marriage certificate;
Birth certificates of children;
Narrative of marital history;
Evidence of the ground;
Witness list;
Psychological report, if applicable;
Property information;
Custody and support claims;
Proof of residence and jurisdictional facts.

B. Filing of Petition

The petition must state the legal ground, facts supporting the ground, reliefs prayed for, children, property regime, and other required matters.

C. Summons and Answer

The respondent is served and may file an answer. If the respondent does not answer, the court may still require the petitioner to prove the case. There is no automatic victory by default in ordinary marriage nullity cases.

D. Role of the Public Prosecutor

The prosecutor or government counsel helps ensure that there is no collusion and that evidence is not fabricated.

E. Trial

The petitioner presents evidence and witnesses. Expert witnesses may testify in psychological incapacity cases. The respondent may cross-examine and present contrary evidence.

F. Decision

If the court grants the petition, it issues a decision declaring the marriage void or annulling it, depending on the ground.

G. Finality, Registration, and Annotation

A favorable judgment must become final and must be properly registered with the civil registry. The decree, partition, liquidation, and custody/support orders must be completed as required. A person should not remarry until the legal requirements are fully satisfied and the civil registry records are properly annotated.

XVII. Prescription and Time Limits

Time limits depend on the action.

A. Declaration of Nullity

Actions for declaration of nullity of void marriages, particularly those based on psychological incapacity, are generally treated differently from ordinary annulment actions. Since the marriage is void from the beginning, the issue is not the same as a voidable marriage.

B. Annulment of Voidable Marriage

Annulment actions based on lack of parental consent, insanity, fraud, force, physical incapacity, or sexually transmissible disease have specific periods for filing. The period depends on the ground and on facts such as discovery of fraud, cessation of force, recovery of sanity, or age of the party.

C. Legal Separation

Legal separation actions must be filed within the period provided by law from the occurrence of the cause. Delay may be fatal.

D. Criminal Complaints

Adultery and concubinage are subject to criminal prescription periods and special filing requirements. Delay, pardon, consent, or failure to include required parties may affect the case.

XVIII. Reconciliation, Forgiveness, and Condonation

In cases involving infidelity, what happens after discovery matters.

A. Effect on Legal Separation

Forgiveness, reconciliation, or resumption of marital life may bar or affect legal separation. If the innocent spouse condones the offense, the legal separation case may be weakened or dismissed.

B. Effect on Criminal Complaints

Pardon or consent may affect the ability to prosecute adultery or concubinage.

C. Effect on Nullity

In psychological incapacity cases, reconciliation does not necessarily validate a void marriage. However, evidence of long periods of normal married life may be used to argue against incapacity.

D. Effect on Annulment

In voidable marriages, ratification or continued voluntary cohabitation after the defect ceases or after discovery of the fraud may bar annulment, depending on the ground.

XIX. Infidelity Before Marriage Versus Infidelity After Marriage

The timing of the affair is legally important.

A. Before Marriage

Infidelity or another relationship before marriage may matter if:

The spouse concealed pregnancy by another man;
The spouse was already married;
The spouse entered marriage without genuine capacity to fulfill marital obligations;
The affair shows a pre-existing psychological incapacity;
The spouse concealed a serious sexually transmissible disease;
The marriage was entered into through fraud or coercion.

B. After Marriage

Infidelity after marriage is more often relevant to:

Legal separation;
Criminal adultery or concubinage;
Custody;
Support;
Property disputes;
Civil damages;
Evidence of psychological incapacity, if connected to a pre-existing condition.

C. Long-Standing Pattern

A pattern that began before marriage and continued afterward is more legally significant than an isolated post-marriage affair.

XX. Infidelity, Abandonment, and Support

A spouse who cohabits with another person may also abandon the family. Abandonment can have legal consequences independent of the affair.

A. Failure to Support

A spouse or parent who stops providing support may face civil and, in some situations, criminal consequences. Support may be demanded through a family court action or as part of related proceedings.

B. Economic Abuse

Where the victim is a woman or child, deprivation of financial support may also be treated as a form of abuse depending on the facts.

C. Constructive Abandonment

A spouse may effectively abandon the family even without physically disappearing, such as by maintaining another household, refusing support, or forcing the spouse and children out of the home.

XXI. Third Party Liability: Can the Lover Be Sued?

In some cases, the third party involved in the affair may face legal consequences.

A. Criminal Liability

A third party may be included in adultery or concubinage complaints if the legal elements are present.

B. Civil Liability

A third party may be sued for damages if their conduct is willful, malicious, humiliating, or directly injurious to the innocent spouse. However, the claim must be supported by evidence and a recognized legal basis.

C. Limits

A spouse cannot automatically obtain annulment merely by suing the third party. The validity of the marriage remains a separate issue.

XXII. Common Misconceptions

Misconception 1: “My spouse cheated, so I can get an annulment.”

Not necessarily. Cheating alone is generally not a ground for annulment.

Misconception 2: “My spouse lives with someone else, so our marriage is automatically void.”

No. Cohabitation with another person does not automatically void the marriage.

Misconception 3: “Adultery or concubinage will dissolve the marriage.”

No. A criminal case may punish the offender but does not dissolve the marriage.

Misconception 4: “A psychological report guarantees annulment.”

No. The court decides based on the totality of evidence.

Misconception 5: “If both spouses agree, the court will grant annulment.”

No. Collusion is prohibited. The State has an interest in the marital status.

Misconception 6: “Legal separation allows remarriage.”

No. Legal separation allows the spouses to live separately but does not dissolve the marriage bond.

Misconception 7: “A spouse who cheated automatically loses custody.”

No. Custody depends on the best interest of the child.

Misconception 8: “A waiver or private agreement can dissolve marriage.”

No. Only a court judgment can annul or declare a marriage void.

XXIII. Practical Legal Strategy

A spouse facing infidelity and cohabitation should first identify the real legal objective.

A. If the Goal Is to Remarry

The proper remedy must be annulment or declaration of nullity, depending on the facts. Infidelity must be connected to a recognized ground such as psychological incapacity or fraud.

B. If the Goal Is to Live Separately

Legal separation, protection orders, custody, support, or property actions may be more appropriate.

C. If the Goal Is Support

A support action may be filed independently or as part of a broader family case.

D. If the Goal Is Custody

The focus should be the child’s welfare, not merely the spouse’s affair.

E. If the Goal Is Accountability

Criminal complaints, civil damages, administrative complaints, or disciplinary remedies may be considered.

F. If the Goal Is Property Protection

The spouse should gather evidence of property, bank transfers, business interests, titles, vehicles, loans, and spending for the third party.

XXIV. Drafting a Petition Based on Infidelity and Cohabitation

A petition should not merely state that the respondent cheated. It should connect the facts to the legal ground.

For psychological incapacity, the petition should allege:

The respondent’s personality history;
Conduct before marriage;
Conduct during marriage;
Pattern of infidelity or cohabitation;
Inability to perform marital obligations;
How the incapacity existed at the time of marriage;
How it became manifest afterward;
Effects on the spouse and children;
Attempts to preserve the marriage;
Why the conduct reflects incapacity, not mere refusal.

For fraud, the petition should identify:

The specific fraudulent act recognized by law;
When it occurred;
When it was discovered;
How it affected consent;
Why the action was filed within the proper period.

For legal separation, the petition should focus on:

The specific act of sexual infidelity or cohabitation;
Dates and places;
Evidence;
Lack of consent, connivance, or condonation;
Custody, support, and property reliefs.

XXV. Practical Evidence Checklist

A spouse considering legal action should gather:

PSA marriage certificate;
PSA birth certificates of children;
Proof of residence;
Photos, messages, videos, or admissions;
Evidence of cohabitation;
Birth certificates of children from the affair;
Receipts or bank transfers to the third party;
Property records;
Medical or psychological records, if relevant;
Police or barangay reports;
Witness names and contact details;
School records of children;
Proof of lack of support;
Proof of violence or abuse, if any;
Timeline of the relationship and marriage;
Previous attempts at reconciliation;
Any written agreements or admissions.

Evidence should be preserved lawfully. Hacking, unauthorized access, identity theft, illegal recording, or privacy violations may create separate legal risks.

XXVI. Effects of a Decree of Annulment or Nullity

If the court grants annulment or declaration of nullity, consequences may include:

Dissolution of the marriage bond, depending on the judgment;
Liquidation of property regime;
Custody arrangement;
Support for children;
Visitation rights;
Delivery of presumptive legitimes where required;
Civil registry annotation;
Capacity to remarry after compliance with legal requirements;
Possible changes in surname use;
Settlement of debts and obligations;
Determination of rights of children.

Children conceived or born before the judgment may have specific legal status depending on the type of case and applicable Family Code provisions. Their rights to support and inheritance must be protected.

XXVII. Settlement and Compromise

Parties may settle property, support, custody, and visitation issues, subject to court approval where required. However, they cannot privately agree to annul a marriage. The status of marriage is not subject to simple private compromise.

A spouse may admit facts, agree on property division, or settle support, but the court must still independently determine whether a legal ground exists.

XXVIII. Conclusion

Infidelity and cohabitation are painful and serious marital violations, but Philippine law does not automatically treat them as grounds for annulment. A spouse who cheats, lives with another person, or forms a second family may be morally and legally at fault, but the marriage is not dissolved merely by that conduct.

For annulment or declaration of nullity, the facts must fit a recognized legal ground. Infidelity may be powerful evidence when it reveals psychological incapacity existing at the time of marriage, legally significant fraud, bigamy, or another defect affecting the validity of the marriage. Otherwise, the more appropriate remedies may be legal separation, criminal complaint, support, custody, property recovery, protection orders, or civil damages.

The key legal question is therefore not simply, “Did the spouse cheat?” but rather: Does the infidelity or cohabitation prove a legally recognized ground to annul or nullify the marriage, or does it support another remedy instead?