I know EXACTLY how you feel, and why your doing it, but you have to stop! Dont let him keep making a fool of you. If he doesnt want a commitment with you, then he doesnt get sex, simple as that, but I would seriously take at look at the relationship, because from what you've said, it doesnt sound like you have any kind of solid foundation for this to even work. What you have between you, seems to be more of a dependency.