Telling her isn't going to work. My partner has some sort of personality disorder, and any time I have tried to mention to him he needs help it is met with a rage episode. You can mention to her that seeing a psychologist would help her feel better if she is stressed out and having a hard time. Telling her she has a BPD is a bad idea.

You can also tell her there are some issues in the relationship that you are having a hard time with. You don't feel like you are being heard and there is a lack of communication and think you both should go to a therapist together to work on this. Don't just say "you have a BPD, get help plz."

I believe my partner shows schizophrenic and narcissistic tendencies. Telling someone like that they have an issue is like walking up to someone with a loaded gun and saying, "I think you should shoot me". It can and will be looked at as a personal attack.

I have attachment issues, anger issues, depression, etc. I only came to terms with it after some of my relationships ended all in the same pattern because of it. She has to learn by herself or with the aide of a therapist. Her behavior actually sounds quite similar to the way I behaved in my prior relationships. I was afraid of being abandoned, thought every issue was a HUGE issue and couldn't handle little criticisms. I was basically a raging B*ch to my prior partners. At the time I didn't think so, but over time I noticed patterns in my relationships. I wish I could turn back time and do things over, and actually talked to my partners and been an equal and supportive person...but I can't. She is lucky she has you who is willing to stick by her and be supportive, but she may need to just learn on her own. If any of my partners told me I had a problem I would have scoffed at it and gotten angry. Now, I finally admit that I do and I work towards changing these behaviors.