People keep leaving and ostracizing me

For context, I'm in college. I'm sitting outside of my class right now because I'm feeling awful and I don't know if I should go back in.

Everyone in my class has their own friends and groups and even if I put effort in the friendship, they always leave me. It's driving me crazy because it has been like this my entire life.

People only take interest when they don't know me. All I've ever received from them is complaints about my behaviour. Even if I communicate, it's not worth it because they never understand. If I do a minor bad thing, they don't know how to talk to me about it and end up seeing me as the bad person. And even if we talk about it, it's of no use bevause they can't emphatize with me.

Some weeks ago I talked with a girl and we got along so well and now she ignores me and I don't understand. I didn't do anything wrong as far as I know.