try to go as easy as possible on him. I take it from what you said he's not very popular? He just may be a possesive friend, explain to him that you need other friends too. It's hard for you and that your other friends feelings are getting hurt because he's taking all of your time. He may just not want to lose you as a friend and he doesn't know how to express that. Just try not to hurt his feelings when you tell him (not that I think you would) and if you tell him nicely and he still gets his feelings hurt then you just need to say..I'm not trying to hurt your feelings, but by doing this YOU'RE hurting MINE. You can't let your entire social life revolve around one person. I hope all goes well!!