This is tough. I have had lots of online friendships and some of which I can say that I have fallin in "like" with, as in I really like them A LOT.

I'm not going to deny your friend's feelings, but I agree with you, how could he love someone he never met? It seems hard for me. I at least have to talk to them on the phone or skype or whatever, then I could see it happening.

I don't think you should play his feelings off as a joke, that might really hurt him. It seems like you don't feel the same way, so let him down gently. Tell him you don't feel the same way, but you love being his friend. Truth always works, instead of dodgy mindgames.