I've noticed before that the most I can stay friends with someone is about seven years. I have a few friends I've known longer than that, but it's usually a situation where we were once friends, grew apart, and reconnected later.
So why can't I maintain friendships? Because my brain associates each person I know with the worst thing that person knows about me. And by the time I've known someone for seven years, that person has had enough negative experiences with me that I can only not think about the terrible things I've said or done to them if I stop interacting with them.
This is the main reason I ended the Personal Board of Directors, and the main reason I have a plan to cut all remaining ties with anyone outside my house. I'm to the point with my dissertation where I might have to quit for the sake of self-preservation, and if I do that, how am I supposed to interact with everyone whom I will have disappointed? I can't go around for eight years telling people I'm going to be a doctor and then be, like, "Just kidding, I'm not smart enough for that," without having it make further interaction impossible.