Should I ask my friend what's wrong?

I know that sometimes, people may ask me about things that I'd rather not share with others. It depends on how close you two are. If he's the type that's quiet, he may not want to talk about it. I think you should ask him if everything's okay. If he says yes, then just don't ask about it again. He may approach you and ask to talk about it. Or then again, he may just be the type of guy that likes to keep things to himself. My advice is too just ask him if everything's alright, and how things are going with his girlfriend.