Do you have a mutual friend that could ask him if he is bi, just to make sure before you tell him about your feelings? I could understand that someone that is straight might get a little freaked out about it and not want to talk to you again. However, if he is bi, there's a chance he likes you the same way, and then there's a chance he doesn't. But I think if he is open to the idea of men being together, he will probably be understanding. I've had friends tell me they had feelings for me, and when I didn't feel the same in return, I still remained their friend. There's something strong about friendship sometimes, at least for me. But either way, you won't know how he feels until you ask him.