It is not adultery if you have already separated If you engage in a sexual relationship with someone while you are still legally married, it is technically adultery even if you and your former partner do not live together anymore and are no longer emotionally or physically in a relationship.

Is it cheating if your seperated?

Couples who are separated, whether informally or legally, are still married in the eyes of the law, regardless of how independent their lives have become. This means that if either spouse has a sexual relationship with another person during the separation period, they have probably committed adultery.