I am 20 and my friend is 21 he has a girlfriend but we have known each other since we were 13 and every so often he makes quick glances at me and when we were young we used to look into each others eyes and one time I thought he was going to kiss me. He makes sex jokes and flirts with me occasionally, this has happened for the last 7 years. I am admittedly Bisexual since I was 15 but now it has gotten to the point where now I am really curious I do sort of have crush on him lately. I thought it was my imagination when we were young but he's started doing it more often. I need some well written advice. Is he Gay, Bisexual, or just joking around. I really need your help!

P.S I haven't told him I have had a crush on him, in case it spoils our friendship

P.S.S I have asked him if he's gay but he just walks away from the question or changes the subject.