If you think that your woman is cheating on you and it bothers you enough to ask other people why are you still sleeping with her? I think that if you are looking to keep the relationship you should find a way to ask her without pinning her in a corner . I say this because if for some reason she has truthfully not cheated on you and you pin her in a corner with assumptions you could risk losing her all together. There is no physical way to tell if a person has cheated on you through sex , but you can tell through questions and the way they respond.