I think you have it hammered in your head from this guy that you are the problem, that it's you that is the screw up. So it seems from you saying "he is giving me chances, etc. etc." He has an equal role in this and is contributing as well. I know when you are dumped, you feel like you are the one that is wrong but how he feels about you does not measure how much self worth you have. He seems very confused about how he feels, and the fact that he is dumping you as often as he changes his clothes is very troubling. Break ups are serious events, it's when you want the relationship to end. It's not intended to be thrown out there only to get lonely and get back together a few days later.
When you get into that cycle of breaking up and getting back together, it's headed down a bad path. He is keeping you hooked until he meets somebody else or you completely lose your mind and never want to be with him again. I'm saying this because I was in a relationship like this through most of college. I was your boyfriend, dumping my girlfriend when I was sick of her but asking for her back when I didn't want her to be with anybody else. We thought love would make it work and conquer all, but it didn't and it doesn't. We were the same people getting back into the same relationship, which didn't work the first time, how would it work the second, third, fourth, etc? I wasn't on my own long enough to really learn from my mistakes, and eventually I found somebody else and my ex was out of my mind. That somebody else put up with the same bullshit I pulled on my ex but was sick of it after a few months and kicked my ass to the curb without any chance of reconciliation. And that is when I finally learned and finally grew up. I respected her immensely for not putting up with my behavior. He is probably going to need the same treatment.
I know you are afraid of losing him, but what are you really losing? Are you really happy or just comfortable? There is more than just one person out there for us. You will be okay. It was scary being alone when my latest ex dumped me but I've become such a better person and grew so much from it that I don't mind being alone anymore. Save yourself the time and energy by breaking it off now and start the healing today.
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.