I have never understood this one thing. Why are people always out to isolate me from my friends?

It's been like this from school. But then in uni, it was still happening, where they would manipulate my few friends into hating me. It was so constant, that sometimes I've even overheard them having those conversations, while they thought I was "asleep". I never understood why. I already didn't have any social skills and making friends was a struggle. Then on top of that people just out to isolate me didn't add up. And now again, there's people always looking for the cracks between our friendship to call up my friend to tell him why I'm sh.it and he shouldn't talk to me. Always pulling him away from me. And then my meltdowns give them good reason to show him. "see? See? She's crazy!" 😞
Why do they want me to not have any friends?