A thick, dark line separates legal separation from divorce. Both involve living apart from your spouse under the terms of a court order, but with a legal separation, you’re still technically married. If you become romantically involved with someone other than your spouse during this time, you’re committing adultery.
Effect on Your Separation
The term “legal separation” -- sometimes called “judicial separation” -- implies that you took steps to get a court order setting the terms under which you and your spouse will live apart. You and your spouse didn’t simply elect to move into different residences with an agreement in place between you. The good news is that committing adultery usually doesn't change the financial terms of your separation decree. But custody terms aren’t immutable. Your spouse can take you back to court and, if she can convince the judge that your affair is distressing your children, the custody terms of your separation order can be modified. The court will base its decision on what is in the best interests of your children.
Effect on Divorce
Another consideration involves whether you and your spouse intend to remain separated forever or one of you is eventually going to file for divorce. Adultery is usually grounds for divorce in states that recognize fault. If your spouse decides to move forward and file for divorce, issues of adultery can sometimes affect property and alimony rights in these states. Your affair might make negotiating a divorce agreement with your spouse difficult or impossible if she has hard feelings, and this could force your case to trial.