Why do I always have to be unsuccessful in love?

I don't know what to do anymore! Every guy I've dated has either cheated on me, treated me horribly and...just lost intrested. I don't know if it's me. My first boyfriend cheated on me. I was stupid to take him back the second time. My friends and family called me out on that. Second boyfriend stopped texting me. He said I was too nice, I don't show enough passion and I don't like taking risk. My third and fourth...same thing.
My fifth boyfriend a year ago dumped me because of my weight (let myself go) and he said I don't take care of myself, I'm lazy, fat and always treated him like shit and screaming when he was trying to help and give honest feedback. Dumping me over my weight was stupid. I mean I admit I let myself go and didn't wanna excersize but still no reason.
I'm so done with guys! I'm done! My most friends are either in relationships or getting engaged. I better not be the last one. Some people from high school are married and have kids of their own. What is going on?!
My friends think I'm too desperate and I need to take time for myself and take care of myself first.