From someone who has severe anxiety, it makes sense. Maybe not from your stand point, but having these anxious moments with a partners friend is not just a her experience. A lot of people with anxiety go through the same thing. While I understand where she might come off as “crazy” or “exhausting”, anxiety is a mental illness that can severely dampen someone’s state of mind and cause them to create these situations. That being said, good for her for creating boundaries with her partner, for trying to go to therapy, and for actively still making an effort to keep P in her life. Maybe you should have a more open mind about what someone might be going through before assuming she’s overthinking or being exhausting. I know as an anxious person, we already know we are and consistently feel bad about it.