Well if you just want to fuck the guy, then leave it as that. He obviously just wants to fuck you. Why make the relationship anything more then what the two of you want. Then when the guy comes around and he wants to get to know you instead of fuck you. That's the guy you should date
Hmm honestly that depends on the person you are and they person they are. If you knew they were a cheater before then why did you date them but if you didn't and you want to give them a chance that's acceptable. But after that second time then no ain't worth it. If it was me I would say fuck you I'm not giving you another chance, but that's just me.