Most Helpful Guy
Stop nagging and complaining. Why can't you just enjoy being with him? Stop worrying about the little things that piss you off... like how he moves the sponge in a counter-clockwise direction when he does the dishes but how EVERYONE knows that the sponge has to go clockwise, why is he so stupid?
I'm exaggerating and I don't mean to insult you. It's a very real problem though and I went through the same thing with my ex. She nagged me about everything. I can tell you that it pushes guys away when you do that. I'm sure you've heard people say that guys visit hookers sometimes just to relieve the stress of being at home... Well, that's why. The nagging is the stress. I'm sure that for a lot of guys they cheat because they are stressed and they just want a girl that's nice to them, even if they have to pay for it.
Maybe he really does love you. Maybe not... moving in with that chick so soon is kind of weird, to be honest. But I'm not judging. You know that song by Big Sean, "Beware"? I swear that applies to guys. Just because they cheat doesn't mean they don't care.
If you really want him then say so. Tell him to come back. No questions, just move on from there. Don't be asking him about what he did with the other girl. Start fresh... and this time no nagging about little things- or find a better way to do it. Maybe you can trade your nagging for him sleeping around. Just a suggestion if you REALLY REALLY want to make it work.