Is it wrong to expect your partner to be faithful to you if...?

I am going through this exact same situation....I don't ever feel it is ever right to cheat on a person. However, it is not right for that person to at least try and get some help and try to remedy the situation. If they refuse, they can not be surprised if you leave. You deserve to be happy to...it is not all about them. However, I am still in my situation because I don't want to leave because of that. But it is not getting easier