Below is a comprehensive discussion of the legal implications of entering into a new intimate relationship after a married couple has separated—whether formally (through legal separation proceedings) or informally (mere de facto separation)—under Philippine law. The matters covered include the relevant statutes (primarily the Family Code of the Philippines, Executive Order No. 209, as amended), pertinent criminal laws (notably the Revised Penal Code), property implications, rights and obligations concerning children, possible civil liabilities, and other socio-legal concerns.

1. Governing Laws

Family Code of the Philippines (Executive Order No. 209, as amended)
- Enacted in 1987, it governs marriage, legal separation, annulment, and related familial rights and obligations.
- Outlines the rights and duties of married individuals, the grounds and process for legal separation, declaration of nullity of marriage, annulment, and separation of property.
Revised Penal Code (Act No. 3815, as amended)
- Defines and penalizes crimes such as adultery, concubinage, bigamy, and other offenses that may arise from relationships outside of marriage.
- Remains relevant to post-separation relationships because, in Philippine law, a valid and subsisting marriage remains protected until legally terminated or declared void.
Special Laws
- Anti-Violence Against Women and Their Children Act of 2004 (Republic Act No. 9262): Psychological violence or emotional abuse stemming from extramarital relationships may be relevant.

2. Status of Marriage Under Philippine Law

2.1 Indissolubility of Marriage (No Absolute Divorce)

The Philippines does not generally recognize absolute divorce (except for Muslims under Presidential Decree No. 1083 and in cases involving foreign divorces under limited conditions in the Family Code and jurisprudence).
Thus, for most Filipinos, marriage subsists unless it is either:
1. Declared null and void from the beginning (void ab initio) on specific legal grounds (e.g., lack of a valid marriage license, psychological incapacity under Article 36 of the Family Code).
2. Annulled (voidable marriage) on grounds such as lack of parental consent (if below 21 at the time of marriage), fraud, force, or intimidation.
3. Terminated by the death of a spouse.

2.2 Legal Separation vs. Annulment/Declaration of Nullity

Legal separation does not sever the marital bond. Instead, it merely allows the spouses to live separately and addresses property arrangements, but they remain legally married.
Annulment or Declaration of Nullity effectively ends or voids the marital union. A final judgment of nullity/annulment is necessary for the spouses to be free to enter another marriage.

3. Post-Separation Relationships and Their Legal Consequences

3.1 De Facto Separation Without Court Approval

Couples who merely separate physically without obtaining a judicial decree of legal separation or a final judgment of annulment/declaration of nullity remain married under the law.
Any intimate relationship with a third person during this period can give rise to criminal, civil, and administrative liabilities.

3.1.1 Possible Criminal Liabilities

Adultery (Article 333, Revised Penal Code)
- Adultery is committed by a married woman who engages in sexual intercourse with a man who is not her husband, and by that man who knows she is married.
- Even if spouses are separated, if there is no judicial decree annulling or declaring the marriage void, the wife’s relationship with another man can be considered adultery.
Concubinage (Article 334, Revised Penal Code)
- Concubinage is committed by a married man under specific circumstances (e.g., cohabiting with a mistress in the conjugal dwelling or having sexual intercourse under scandalous circumstances, or keeping a mistress in another place).
- Simply put, if a married man, without benefit of a legal separation decree or annulment, publicly cohabits with another woman, this can be seen as concubinage.
Bigamy (Article 349, Revised Penal Code)
- Bigamy arises when a person who is validly married contracts a second or subsequent marriage without the prior marriage being annulled or declared void.
- Even if spouses are “separated in fact,” contracting another marriage (often through a ceremony abroad or in a different jurisdiction) is criminally punishable.

3.1.2 Other Potential Liabilities

Psychological Violence under R.A. 9262
- Engaging in an extramarital affair that causes emotional or psychological suffering to the legal spouse may constitute psychological violence under the Anti-Violence Against Women and Their Children Act.
Civil Damages
- The offended spouse may file a civil case for damages against the spouse and/or the third party if the extramarital relationship caused injury or damage to the offended spouse, although these cases are less common and often require proof of actual harm.

3.2 Post-Legal Separation Relationships

Even after securing a judicial decree of legal separation, the parties are still considered legally married. The main differences under legal separation are:
1. Spouses are allowed to live separately.
2. Certain property relations are settled or separated under the terms of the decree.
3. The court may decide on custody and support arrangements.
Despite the separation, neither spouse can lawfully remarry or engage in a new marital union. If they do, they can still be held liable for concubinage, adultery, or even bigamy if there is a new marriage contract.
Although many people believe that a decree of legal separation grants some “freedom,” it does not dissolve the marriage bond.

4. Property Relations and Implications

4.1 Conjugal and Community Property

Under the Family Code, the default property regime for marriages celebrated after August 3, 1988, is the Absolute Community of Property (ACP) unless the spouses have a pre-nuptial agreement establishing another regime (such as the Conjugal Partnership of Gains, Complete Separation of Property, etc.).
If spouses separate (either physically or via a legal separation decree), any property acquired during the subsistence of marriage remains subject to the rules of the ACP or the conjugal partnership, as applicable.
Judicial separation of property can be decreed by the court in cases of legal separation or other justified circumstances.

4.2 Effects of Extramarital Relationships on Property Rights

A spouse who misuses or dissipates the couple’s property in favor of a paramour can face legal consequences, including:
- Possible forfeiture of their share in favor of common children or the offended spouse (Article 63 and 64 of the Family Code, in cases of legal separation).
- Being held liable for damages or restitution if the offended spouse proves financial loss or fraud.

5. Effects on Children (Legitimate and Illegitimate)

Legitimate Children
- Those conceived or born during a valid marriage are considered legitimate, even if the parents later separate.
- They retain rights to support, inheritance, and all other entitlements of legitimate children.
Children Born Out of an Extramarital Relationship
- Children born out of extramarital affairs are considered illegitimate if the marriage with the legal spouse is still subsisting.
- Illegitimate children are entitled to support from the biological parent and have inheritance rights (though less than legitimate children’s share, and subject to certain conditions in the Civil Code and Family Code).
Custody and Support Issues
- The Family Code and jurisprudence emphasize the best interest of the child as the primary consideration.
- A parent’s extramarital affair alone does not automatically disqualify him/her from custody, but if it negatively affects the welfare of the child, courts may consider it a factor in custody decisions.

6. Annulment and Declaration of Nullity of Marriage

6.1 Grounds and Processes

Declaration of Nullity: Filed when the marriage is void ab initio (e.g., lack of essential or formal requisites, psychological incapacity under Article 36).
Annulment: Filed when the marriage was valid but becomes voidable due to grounds existing at the time of marriage (e.g., lack of parental consent if under 21, fraud, force, impotence, serious mental illness).
Once a final judgment is rendered declaring the marriage void or annulling it, the parties are free to remarry.

6.2 Relevance to Post-Separation Relationships

If individuals wish to be free from the criminal and civil risks associated with extramarital relationships, they must secure:
1. A final decree of annulment or declaration of nullity of marriage, or
2. Ensure that the prior marriage was validly terminated (death of a spouse, or recognized foreign divorce under limited circumstances).

7. Social and Ethical Considerations

While the legal system imposes penalties on spouses who form intimate relationships before the marriage is legally dissolved, social perceptions vary. Some separated spouses enter new relationships due to irreconcilable differences or in anticipation of an annulment that might take years.
However, the legal reality remains that the risk of criminal prosecution and civil liability is present, especially if the offended spouse decides to file a complaint.

8. Practical Tips and Recommendations

Seek Legal Advice Early
- If contemplating separation, obtain counsel regarding the repercussions of a new relationship.
- Understanding procedural timelines and evidentiary requirements for annulment or legal separation helps in planning and avoiding legal pitfalls.
Maintain Documentation
- Keep records of property ownership, financial transactions, child support agreements, and any relevant communications with your spouse.
- Proof is crucial in cases of property dispute, custody, and potential criminal or civil actions.
Consider the Welfare of the Children
- Regardless of marital conflicts, the best interests of the children should be prioritized.
- Courts will look unfavorably upon any parent who neglects or adversely affects the well-being of children.
Explore Mediation or Counseling
- While not always feasible, mediation or counseling can sometimes help clarify rights and obligations.
- Out-of-court settlements on property and custody/support can reduce conflict and expedite resolution.
Exercise Caution in Public Displays of a New Relationship
- Public cohabitation or overt evidence of an extramarital affair can form the basis for a criminal complaint.
- Discretion is recommended to avoid unnecessary legal complications.

9. Conclusion

In the Philippines, marriage is accorded stringent legal protection and is not easily dissolved. Once married, spouses remain bound to each other and to the obligations of marriage until they obtain a final decree of annulment, declaration of nullity, or experience the death of a spouse. Post-separation relationships (whether de facto separation or under legal separation) expose the involved parties to potential criminal liability (adultery, concubinage, bigamy), civil damages, and complications in property and child custody matters.

The conservative legal framework underscores the importance of proceeding carefully when a marriage has broken down. Those intending to move on to a new relationship are strongly advised to secure legal counsel and consider filing an appropriate court action to avoid the many pitfalls. Until the marriage is legally severed, both the emotional and legal risks remain substantial.