The legal consequences of adultery depend on three things: the state you live in, whether you’re in the military, and what you signed before you got married. In most situations the real damage shows up in divorce court, where an affair can reduce what you receive in alimony, shrink your share of marital property, and in a handful of states even expose your partner to a lawsuit from your spouse. Criminal charges are theoretically possible in about sixteen states but almost never filed. Military members face a separate and much harsher system.
Here’s what each of those tracks actually looks like.
How Adultery Affects a Divorce
Roughly two-thirds of states still recognize fault-based divorce, and adultery is one of the most common fault grounds. Filing on fault means proving the misconduct with real evidence: text messages, financial records, photographs, witness testimony. Suspicion isn’t enough.
Every state also offers no-fault divorce, which doesn’t require proving anyone did anything wrong. But evidence of an affair doesn’t disappear just because the filing is no-fault. Judges can still weigh it when they decide money questions like spousal support and property division.
One reason some spouses still pursue a fault filing is timing. Several states require a mandatory separation period before granting a no-fault divorce, sometimes a full year. A clear-cut, uncontested fault filing can sometimes skip that waiting period. The tradeoff is that proving fault costs time and money too, so the speed advantage isn’t guaranteed.
Alimony
This is where adultery most often does measurable damage. A significant number of states treat marital misconduct as a relevant factor in alimony. In a handful of states, a spouse whose adultery caused the divorce can be barred from receiving alimony at all. In most states that consider fault, the judge has discretion to reduce or deny support based on the circumstances.
Courts tend to look at the broader picture. Did the affair cause financial harm to the other spouse? Was marital income spent on the relationship? How long was the marriage, and what are each person’s financial needs? Adultery by itself rarely flips an alimony ruling, but combined with financial misconduct it can shift the outcome substantially.
Dissipation of Marital Assets
When a spouse spends marital money on an affair, the other spouse can raise a dissipation claim during property division. Dissipation means one spouse used shared assets for purposes unrelated to the marriage after the relationship had already begun breaking down. Hotel rooms, gifts, trips, and restaurant tabs for an affair partner all qualify. If the claim succeeds, the judge can reduce the offending spouse’s share of marital property to reimburse the estate for what was spent.
These claims aren’t automatic. The spouse alleging dissipation generally needs to identify the specific assets wasted, produce financial records, and show the spending happened after the marriage was already in trouble. Vague accusations without documentation rarely get traction. With a clear paper trail, dissipation can meaningfully change the division.
Does Adultery Affect Child Custody?
Usually not. Courts decide custody based on the best interests of the child, looking at each parent’s ability to provide a stable home, the quality of the parent-child relationship, and each parent’s mental and physical health. An affair, standing alone, doesn’t say much about whether someone is a good parent.
The exception is when the affair directly harmed the child or created an unsafe environment. If the relationship led to neglect, or if the affair partner has a history of violence or substance abuse and is around the children, those facts become relevant. A parent who disappeared for days at a time and left the children without proper care will face scrutiny. But the scrutiny is about the parenting failure, not the infidelity itself.
Infidelity Clauses in Prenups and Postnups
Couples can build financial penalties for adultery directly into a prenuptial or postnuptial agreement. Sometimes called lifestyle or fidelity clauses, these provisions attach a specific consequence to infidelity: a lump-sum payment, higher spousal support, or a shift in how assets get divided at divorce. Some are reciprocal; some apply to only one spouse.
Whether they actually hold up is the open question. Most courts that have addressed infidelity clauses have upheld them under the general rule that spouses can contract about anything not prohibited by public policy. But a few courts have refused to enforce them, reasoning that penalty clauses tied to marital conduct conflict with no-fault divorce principles. The law here is still developing, and a clause that would be enforced in one state might be struck down in another. Anyone counting on one should talk to a family law attorney in their jurisdiction before relying on it.
Criminal Adultery Laws
Adultery is still a crime in roughly 16 states. In three of them it’s a felony, with potential prison sentences of several years. In the rest it’s a misdemeanor, ranging from modest fines to up to a year in jail. One state repealed its criminal adultery statute as recently as late 2024.
Actual prosecutions are extraordinarily rare. Proving what happened behind closed doors is difficult, and most prosecutors consider these cases a poor use of resources. The statutes aren’t entirely toothless, though. The laws occasionally surface in divorce proceedings or military investigations where a party’s conduct is already under scrutiny, and a conviction, however unlikely, is still a criminal conviction.
Civil Lawsuits by the Betrayed Spouse Against the Affair Partner
About seven states still let a betrayed spouse sue the affair partner directly. These “heart balm” torts come in two forms. Alienation of affection requires showing that the third party’s conduct destroyed the love and affection in the marriage. Criminal conversation is more straightforward: it requires proof that the third party had sexual intercourse with the married spouse. Both are brought against the outside party, not the unfaithful spouse.
Damages can be significant. Jury awards have occasionally reached into the millions, with one notable verdict combining compensatory and punitive damages for nearly $9 million. Those are outliers, but they show the exposure is real. If you’re involved with a married person in one of the states that still recognize these claims, you can be personally sued regardless of what happens in the divorce.
Adultery in the Military
The military treats adultery far more seriously than civilian law does. Under Article 134 of the Uniform Code of Military Justice, extramarital sexual conduct is a chargeable offense when three elements are met: the service member had sexual intercourse with someone, one of the parties was married to someone else at the time, and the conduct was prejudicial to good order and discipline or brought discredit upon the armed forces.1Office of the Law Revision Counsel. 10 USC 934 Art. 134 General Article That third element is where military law really diverges from civilian courts, because the question isn’t just whether the conduct happened but whether it undermined the unit or the service’s reputation.2United States Army. Legal Separation, Adultery and the UCMJ
The potential consequences are severe. A service member found guilty can face court-martial, confinement for up to one year, forfeiture of pay and allowances, and a dishonorable discharge. Short of court-martial, non-judicial punishment under Article 15 can bring reduction in rank, extra duty, and restriction of privileges. A dishonorable discharge follows you into civilian life, affecting employment, veterans’ benefits, and firearm rights.
Legal separation now serves as a recognized defense to extramarital sexual conduct charges, provided both parties to the conduct are either legally separated or unmarried. If only one party is legally separated and the other is still in an intact marriage, the defense doesn’t apply. The safest course for any service member is still to avoid a new sexual relationship until the divorce is final, because the line between “legally separated enough” and “still exposed” is genuinely unclear.2United States Army. Legal Separation, Adultery and the UCMJ