Why do guys do this?

There is this guy, we have been friends for 4 years now. After 4 years of friendship he want to say that he likes me. But when I want to talk to him about it. He doesn’t want to talk about it. So I figured that maybe one of his close friends will convice him to sit and talk about how he feels about me. But he says that he never said that. But I heard him say it and he meant it. There is a little tension in our friendship now, because he doesn’t want to talk to me about it.

Ever since he told me how he felt, I had feelings for him. How can I get him to open up, without going to far?
Its making me mad that he doesn’t want to talk about it, he just want to keep it to himself