Adultery as Grounds
If you live in a no-fault state, your spouse can't divorce you because you committed adultery. He's limited to grounds such as irreconcilable differences or irretrievable breakdown of the marriage, and he typically cannot present evidence or allegations that you did something wrong to end the marriage. Some exceptions exist, however. Although your spouse can't charge you with adultery as grounds, he can potentially use your affair to affect aspects of your divorce, even in a no-fault state. In most fault-based divorce states, adultery can also be used as grounds. In either case, legal rights are mostly on the side of the innocent spouse. He should not suffer undue financial hardship because you committed adultery and it ended the marriage; this would effectively punish him because you had an affair, and most courts recognize this.
Burden of Proof
It's never enough for your spouse to simply accuse you of committing adultery. He has the burden of proof to convince the court that it really did occur. This is not to say that he must catch you in the act, but most states require that he establish you were of a mind to stray and that you had the opportunity to do so. In effect, you're innocent until your spouse proves you're guilty by a preponderance of the evidence. Your spouse can prove your inclination by establishing, through third-party testimony, photographs or other evidence that you had romantic feelings toward someone else. He can prove opportunity by establishing that you disappeared into a motel room with your paramour for several hours. In some states, such as Maryland, your spouse must produce this sort of evidence at trial even if you admit to the affair. A judge won't take your word for it either, because it may have financial repercussions.
If your spouse does raise the specter of infidelity in the process of your divorce, you have the right to defend yourself. You can only do so within statutory guidelines, however. For example, you can allege condonation on the party of your spouse. This involves proving that he effectively forgave you after your affair, such as by resuming your marital relationship after he found out about it. You can file a defense on grounds of recrimination, citing that your spouse also committed some marital wrongdoing. In this case, your fault-based actions offset each other. A defense of connivance means that your spouse was not only aware of your extramarital affair, but he encouraged it in some fashion and gave it his blessing. Establishing a defense can neutralize the effect of adultery on your divorce proceedings, even if your spouse is looking for some sort of damages because you strayed. You also have a burden of proof to establish your defense.
Effect on Divorce
Adultery typically affects issues of property division and occasionally alimony. For example, in Virginia, you give up the right to alimony if you've been unfaithful. You might be able to overcome this bar if you can prove that you'd be left literally destitute without your spouse's financial support, but this typically applies only in extreme circumstances. More likely, if you spent marital money on your paramour, the court will compensate your spouse for this – he has a right to a share of the money you spent on someone else, just as if the money or assets had remained intact. A court might make an uneven division of marital property, awarding your spouse more of the assets and money that remain, even in a community property state. If you have children, adultery does not normally affect custody rights. Most states base custody on the best interests of the child, so your spouse would have to prove that your affair caused your children psychological harm.