Dating dilemma

[ilovemyglo]

Okay I had to dig up this post so I can update and ask for your help again!
Okay I ended up dating Jack again.. we have been back together for six months. Things have been better than I thought they could ever be. He has been sincere, loving, caring.. we have had a great time together and he has shown me nothing but support and love. My family spent a lot of time with him this summer and they love him too! He gets along with everyone and I adore him. I had a terrible breakup a few years back and I hadn't loved anyone that much.. until now.
So here is the problem. Things went from bliss to huh in 2.5 seconds!!
He went from wanting me around and wanting more time than I had (which sounds weird) to not caring when he sees me or if he sees me! It used to be that if I didn't come over every night he was torn up, now if I don't come over it is almost like he is relieved. This has only been 2 weeks (TOPS!). So of course I asked him about it. He said he has been depressed and really just doesn't want to be around people. He was really honest and told me he just wonders what it would be like to be without me, but that he loves me and doesn't want to break up (kind of like, "Can I live without her?" type deal). So he then told me not to worry because it will pass and that things are going to be fine because he doesn't want to break up, he just wants us to do our thing for now. So of course I freak out and that upsets him.
So, do I give him space? For how long? What if he decides he doesn't want me? Why are guys like this? They want something so badly and when they get it, they flip! The worst part is I finally fell so in love with someone and now, I may lose him and my heart. I don't think I could ever get over that.
So that is the story.. oh and Ernie is coming in town soon and wants to hang out and then Todd will barely speak to me cause I am back with Jack and now he does and i miss him being around (as a friend). But Jack gets jealous when I am over there.