It's still rare, but sometimes it's the girl doing most of the work...
Waiting for the right one or extreme shyness are actually possible, if I were straight I would be in that situation...
But there's a little detail that must not be underestimated: "I think". Some things just happen in a certain way and there's nothing and no one to blame for that... Why should it be your fault? You just came out to him, so that's not it; being too much around him? Check the paragraph below, I didn't spell that out, but between those problems and our friendship you could have found me around my best friend anytime I could, but it worked out fine... Experimenting with each other? It's not like you forced him to, and he also had a life before college, if he wanted to he could have had girls before you two even met...
Few years ago I was having some depressive problems, my best friend was basically the only one keeping up with me, I actually worried about him, having to bear my problems instead of having fun, getting a girlfriend and that kind of stuff... He kept working with me on my depression for years and still got girlfriends....