I can't say for sure why you have a hard time dealing with the idea of losing him. In my case, maybe it was easier for me because I always knew what we had was temporary and never entertained any thought of it being permanent. If you've been letting your mind fantasize about it always being the same with him, maybe that's making it harder to let him go. I've always been pretty honest with myself, even when it hurts. It's less painful in the long run.

Keep in mind that letting go is a gradual thing, not an all or nothing thing. Yes, he will eventually drift more into his own world and less into yours. But you'll still have plenty of good times during the transition to adulthood. Cherish those times and lock them away in your memory to help you thru the hard times.

Dakota