What is it about feeding your worst fears that brings you so much comfort?

Stating the obvious here, but I don't like things to go unsaid:

If you want to quit being "needy" wrt expecting him to fill all the gaps, I'm sure you're well aware that its your responsibility to do so. You've been back half a year, its about time to make new friends and forge new bonds.

Are you perhaps grieving your lost friendships but occupying your head with other heartbreaking ideas so as not to admit to your loss? To justify your sadness perhaps...

Or are you perhaps entertaining these thoughts because you fear you will lose him too and have nobody? Sort of like preparing for what you may percieve to be inevitable.

Time for you to issue yourself with a reality check.

Truth is, if you continue to entertain these morbid ideas to the point of it affecting your relationship, your sleep and who knows what else, you will lose your bf.

Question is, will it be worth it?

If the answer is no, then I suggest you address what's really hurting you and put your imagination to bed for a while. I also suggest you seek out a therapist to help guide you along if you're unable to work through it alone.