yes she was but she minimised it. She told me "they" (the Social services) had diagnosed her with BPD after her suicide attempt and subsequent sectioning by the state. She was "not convinced" by their diagnosis.
She asked me once to come with her to a session to support her. There was a psychologist and a high ranking NHS psychiatrist present. It was intense but she was cool as a cucumber and played them like little kittens

Damn! It was impressive. She was composed and articulate and could have sold snow to an eskimo that day. a masterclass in bluffing!
The big cat even said she was coping incredibly well and was at the lower end of the BPD scale ie. high functioning and recovering!. They asked me my thoughts and experiences and in disbelief I sidestepped this with a generic response. They were easy going with their treatment options. she had to attend a monthly session as well as work on a DBT workbook at home (which she never).
That woman was slick in public, I have to give her that. World Class
it was around this time that she began to be grandiose and dominant, losing all humility. It was a victory for her and from that day on all of the problems were mine and I was the sick and dysfunctional one. tbh, I see this as the big turning point. Things got really bad.
At the end, she flipped it all, accused me of being BPD and even gave me her DBT workbook

Similar thing here! After a huge dysregation, cheating and near psychoses I said go to therapy or Im gone... .He went and I went with him. In that session he played the waif (he's actually hermit/king) and he got diagnosed. I wasnt invited to any other sessions, but every week he would come back from therapy saying how well he was doing when things actually were getting worse. I think he played his T. like an organ. In the end he said I made him go to therapy while was the sane one. His T. had said I was the BPD one and I belonged in a mental institution.
I had to hear this so often that I asked my T. if she thought it was true. Nope codep. traits, no BPD. I still had doubts and went as far as asking my non exbf (before my rs with exBPD) how they saw me in our rs. He also agreed I wasnt BPD.
I do think it might have rubbed of a bit on me. At the end of the rs I was having difficulties with staying calm and collective. I reacted to his nonsense quite unhealthy at times. Never knew I had that in me.
I really think its hard for high functioning BPD's to submit to getting help and taking it serious.