If he's cheating on you then show him the door... simple... he would never accept you cheating so why should you... and for all those "idiots" who are telling you its a normal thing as a guy, I think they are talking a lot of BS...when you marry you marry with the aim of staying together... if you cannot keep it in your pants (Guys)or gals then separate and go your own ways... Being unfaithful is something that no matter how many times you say you will forgive never happens... its there in your mind forever and eats away at you.....