The short, practical answer

Yes—but only in a specific setup. In Philippine law, adultery and concubinage are crimes that exist to protect a valid marriage. So:

If you are legally married to someone, and your spouse is living in (or having a relationship) with another person, you may be able to file:
- Adultery (if the wife is the one cheating, with a man), or
- Concubinage (if the husband is the one cheating, with a woman), and you generally must include BOTH your spouse and the live-in partner in the criminal complaint.
If you are not married to your live-in partner (i.e., you are only cohabiting), you cannot file adultery or concubinage based on your partner’s cheating, because there is no marriage to protect under these crimes.

Everything else in this article explains the “why,” the elements, what can and can’t be filed, and the common issues that decide whether a case survives.

1) What adultery and concubinage are (and why marriage is the key)

Adultery

Adultery is committed by:

a married woman who has sexual intercourse with a man who is not her husband, and
the man who has sexual intercourse with her knowing she is married.

Important: Adultery is specifically framed around a married woman and a male sexual partner.

Concubinage

Concubinage is committed by:

a married man who engages in certain forms of infidelity with a woman who is not his wife, and
the woman (the “concubine”) if the legal requirements are met.

Concubinage is not “any cheating.” It has specific modes (explained below).

Why a live-in setup matters

A “live-in partner” can mean two very different legal realities:

Live-in partner of a legally married person Example: Your husband moves in with another woman. → This can fall under concubinage if the legal elements are present.
Live-in partner with no legal marriage between you and that partner Example: You and your partner have been cohabiting for years but never married, and they move in with someone else. → You cannot use adultery/concubinage, because these crimes require a valid marriage involving the offended spouse.

2) Who can file: only the “offended spouse”

Adultery and concubinage are treated as private crimes. In practical terms:

Only the offended spouse (the spouse betrayed in the marriage) can start the criminal case by filing a complaint.
A girlfriend/boyfriend/live-in partner who is not a legal spouse cannot file adultery/concubinage for being cheated on.
Even close relatives generally cannot file these cases in your place (with very limited exceptions in other private crimes—not typically applicable here the way it is for adultery/concubinage).

3) Can you file a case “against the live-in partner only”?

Generally, no. The criminal complaint must usually include both guilty parties:

Adultery: the married woman and the man who knew she was married.
Concubinage: the married man and the concubine.

As a rule, you cannot selectively prosecute just the third party while excusing your spouse, because the law views the offense as involving both participants.

Practical effect: If your goal is to “go after the kabit only,” adultery/concubinage is usually not the right tool.

4) The legal elements you must prove

A. Adultery: what must be shown

To have a viable adultery case, the complaint/prosecution must generally establish:

The woman is legally married.
She had sexual intercourse with a man who is not her husband.
The man knew she was married.

Key point: Adultery focuses on sexual intercourse, not just cohabitation, sweet messages, or public dating. Evidence must reasonably show intercourse occurred (often through admissions, witness testimony on circumstances strongly indicating it, hotel records with corroboration, pregnancy with timing, etc.).

B. Concubinage: what must be shown (and why it’s harder)

Concubinage is committed by a married man who does any of the following:

Keeps a mistress in the conjugal dwelling (the marital home), OR
Has sexual intercourse under scandalous circumstances, OR
Cohabits with a woman in any other place (i.e., they live together as a couple somewhere else).

Key point: Concubinage is more technical and often harder to prove than adultery because it requires one of those modes—not merely proof of sex once.

5) If you’re the spouse: which case applies—adultery or concubinage?

It depends on who is legally married and their sex under the statute:

If the wife (married woman) is cheating with a man → Adultery (if intercourse can be proved).
If the husband (married man) is cheating with a woman → Concubinage (if one of the statutory modes can be proved).

If the facts don’t match the statute’s structure (for example, same-sex relationships), adultery/concubinage may not fit cleanly as charged—though other remedies may still exist (see Section 10).

6) What if you and your partner are only live-in (not married)?

If you are not legally married to the person who cheated:

No adultery
No concubinage

Even if:

you lived together for many years,
you have children,
you have shared property,
the community considers you “mag-asawa,”

…these do not create the specific marriage element required by adultery/concubinage.

That said, you may still have other legal options (civil, family, or protective remedies), depending on facts (see Section 10).

7) What if the cheating spouse claims “our marriage is void”?

Adultery/concubinage requires proof of an existing valid marriage as an element.

Real-world complication: Some accused spouses argue the marriage is void (e.g., lack of license, psychological incapacity claims, prior marriage, etc.). Outcomes depend heavily on the facts and how the courts treat the marriage issue in the criminal context.

Practical takeaway: If validity of marriage is likely to be contested, it can become a major battleground that may determine whether the case proceeds. This is one of the situations where lawyer-guided strategy matters a lot.

8) Consent, pardon, and why timing matters

These cases can be blocked if the offended spouse consented or pardoned.

Consent generally means the offended spouse allowed or tolerated the relationship before or during the acts in a way that legally counts as consent.
Pardon generally refers to forgiveness after knowledge of the offense—sometimes shown by actions that clearly indicate forgiveness.

Practical risks:

Continuing to live with the spouse after discovering the affair,
Publicly reconciling, or
Written communications forgiving the act,

…can become issues that the defense may use to argue consent/pardon. These questions are extremely fact-specific.

9) Evidence: what usually matters (and what often isn’t enough)

Often useful

Proof of valid marriage (marriage certificate).
Proof of cohabitation (for concubinage mode 3): leases, neighbors’ testimony, barangay records, utilities, social media showing shared residence plus independent corroboration.
Proof connecting the accused to the conjugal dwelling (for concubinage mode 1).
Proof of scandalous circumstances (for concubinage mode 2): highly public, notorious conduct with witnesses.
Corroborated proof strongly indicating sexual intercourse (especially for adultery), such as admissions plus circumstances, not just rumors.

Often not enough by itself

Screenshots of sweet messages without corroboration.
“Marites” testimony with no personal knowledge.
Mere proof they dated or traveled together (unless tied to proof of intercourse/cohabitation in the statutory mode).

10) If adultery/concubinage doesn’t fit, what other remedies might exist?

A. Legal separation (civil case)

Sexual infidelity is a common ground in legal separation (separate from criminal prosecution). Legal separation can affect:

property relations (depending on regime and court orders),
the right to cohabit,
and other civil consequences.

Legal separation is not a criminal conviction and doesn’t send someone to jail, but it can be a major legal tool in restructuring rights/obligations.

B. Violence Against Women and Their Children (RA 9262) — in some situations

If the offender is a man and the victim is a woman who is:

his wife or former wife, or
a woman with whom he has or had a dating/sexual relationship, or
a woman with whom he has a common child, and the acts constitute psychological, emotional, economic, or other legally defined abuse,

then RA 9262 may be relevant, including possible protection orders.

This is not an “infidelity law,” but infidelity-related conduct can sometimes be part of psychological/economic abuse depending on what was done.

C. Child support / custody / parental authority issues

If there are children:

Support obligations exist regardless of marital status of parents.
Custody and visitation disputes may be handled under family law principles focused on the child’s best interests.

D. Property disputes for live-in couples

If you were only cohabiting, disputes often revolve around:

ownership shares,
contributions,
and the applicable rules on property relations of couples who lived together without marriage.

E. Damages (civil claims)

Sometimes parties explore civil claims for damages based on wrongful acts. Courts are cautious and outcomes depend greatly on the factual theory and evidence. This is not a plug-and-play substitute for adultery/concubinage.

11) Procedure: how these cases are typically initiated

While details vary by locality and circumstances, the general path is:

Complaint-affidavit filed by the offended spouse with the Office of the Prosecutor.
Preliminary investigation (submission of affidavits and evidence; counter-affidavits by respondents).
Prosecutor’s resolution on probable cause.
If found, filing of Information in court and the criminal case proceeds.

Because these are private crimes, the offended spouse’s role and participation are central from the start.

12) Penalties (high-level overview)

Penalties differ between adultery and concubinage and also differ between the spouse and the third party in concubinage. In addition to criminal penalties, conviction can carry collateral consequences (employment, reputation, immigration, etc.), and the process itself is burdensome.

Because penalties and strategy depend on exact charge and facts, it’s best to treat the penalty discussion as case-specific.

13) Common “live-in partner” scenarios and what the law tends to allow

Scenario 1: You are legally married; your spouse lives in with another person

Possible adultery/concubinage depending on facts.
You generally must file against both spouse and live-in partner.

Scenario 2: You are not married; your live-in partner cheats and lives in with someone else

No adultery/concubinage available to you.
Consider family/civil remedies (support, property, protection orders where applicable).

Scenario 3: Your spouse is married to you, but you’re separated in fact (not legally)

Separation in fact does not automatically remove the possibility of adultery/concubinage.
Defenses (including issues like pardon/consent) become fact-dependent.

Scenario 4: Your spouse’s relationship is same-sex

Adultery/concubinage were drafted in gendered terms and may not fit cleanly as charged.
Other remedies may still apply (legal separation, civil/family remedies, protection orders depending on facts).

Bottom line

You can file adultery or concubinage against a live-in partner only if:

there is a valid existing marriage, and
you are the offended spouse, and
the facts satisfy the exact elements of adultery or concubinage, and
you generally file against both your spouse and the third party (the live-in partner).

If you want, tell me which situation fits you best (married/not married; husband/wife; living together elsewhere vs in the marital home), and I’ll map it to the most likely legal options and what typically needs to be proven—still in article-style, but tailored to your facts.