In this situation, I'd try to be firm with him. I'd try to know what was going on inside his mind. I'd want answers. It's one thing to never talk to him again, it's another wanting to know why he changed. Would you feel alright, knowing that you felt you could never see him again? I've seen people become bitter and estranged. It isn't a nice thing to witness. I'm just worried that not talking to him, might turn you into an estranged person. Communication can solve a lot of things. Surely it's worth a try. Nothing is definite. If you want to know why he's been like this with you though, then maybe just ask him if it's alright to talk to him about "something important".