Trusting People Again

I like how my last journal was about trusting people. I keep trying to build friendships and relationships and it all seems to blow back in my face. I don't just choose a person I randomly met a few months ago. This always happens when I've known a person for years.
I was part of a young adults group that just hungout, played video games, go to the movies, go to dinners, and just had a generally nice time. A select few people hungout with me outside of the group and our friendship would grow. Or I thought it was growing. But, it turns out they didn't care about me in the end. One wanted to have a relationship with me, even tho I said I was in one anyway. The other few just completely abandoned me. Stopped returning my texts, stopped calling, stopped hanging out with me, ignored me when I was right next to them trying to talk to them. I have no idea what makes people act like that because I never do anything mean, rude, or hurtful and try to be understanding and nice to everybody. This was a few months ago, around June 2015.
In July 2015 I stopped being friends with one guy because he was very manipulative. He would randomly do favors for you out of nowhere and later down the road wanted you to do stuff for him. If you refused, he'd cuss you out and tarnish any kind of reputation you might have by starting lies. He randomly cussed me out one day and I stopped talking to him. I blocked him from everything online and didn't return his calls or texts. The only reason he cussed me out was because he wanted me to say hi to someone who doesn't want to talk to him anymore. He spread lies online about me and asking random people for my address so he can find where I live. I was waiting for this to all build up so I could get more proof of his harassment and notify the police. He eventually stopped talking about me, at least on public online accounts. This guy has some serious mental problems anyway, but I still would not dare to be his friend anymore.
In August 2015 I start forming a close bond with a girl who I mainly talked to online for a few years. We talked more and more and lived in the same area. So we decide to hangout. Things are going fine for a few months, we never had any arguments or any rough times. We always had a good time together. Then all of a sudden she says that she essentially wants nothing to do with me anymore. I ask why and she just says to not talk to her or call. This was out of nowhere. I've never done anything terrible to anyone, so idk why people do this to me.
If I was being an asshole or maybe offended some people I'd try to change those parts of myself so I wont lose friends. But, I cant see anything wrong that people might hate. So, that bothered me for a while because I thought I finally found a true friend that lives close to me. I was putting my guard down and slowly trying to feel like I was worth something in a friendship-like way. But, they just toss me aside like other people always have.
I keep trying to trust people that I've known for years. And every time I do, they just all of a sudden don't care about me or find someone else to care about even more. I'm trying not to give up on forming relationships with people, but this has been happening my whole life. I don't know why I keep trying. It always ends up with me feeling worse than I did when I was alone. I have my boyfriend and a handful of other people. But, I'm really only close to my bf and one other person. Maybe that's all I need.