I wouldn't worry too much about your friend. Most guys get tired of clingy/hanging girls after a while. Give him your number and say something nice, like a good friend would say when leaving. "I'll keep in touch, okay?" or something simple like that. If you keep in touch often, he may end up liking you back. But don't call or email him every day, or even every other day. That would just be clingy, like your friend is. Just keep a casual long distance relationship, and take it from there.