If lots of people are telling you the guy has a girlfriend, he probably has. Especially if he’s not talking with you after your fight. I don’t know the guy so I might be judging him wrong, but I’m guessing he knows he’s been caught.
For me the big issue would be the problem of him not talking. If he won’t communicate with you after your first fight and try to work things out, he doesn’t sound like a very good partner. I can’t imagine things getting any easier in the future so I don’t think you should bother with him.