As a disclaimer, I am not diagnosed with BPD. I am currently diagnosed with bipolar disorder, and am seeking a more accurate diagnosis with my therapist as we no longer believe it to represent who I am. My therapist and I were discussing the possibility of my having BPD, and she ruled it out as a diagnosis for me because I don't actively split and get aggressive and criticize her.

The thing is, I do split. I have idealized her, and then thought she was hopeless and couldn't help me. I just don't verbally attack her, or other people, for it. However, in her mind, people with BPD must very obviously and publicly split, and deserve to make other people, like their therapists, feel awful about themselves in the moment. She describes it as a vengeful process in which the person with BPD wants to make the other person feel miserable for how they've failed them, and she seems to think they can't help but express this.

Is this true? Do people with BPD fundamentally have to behave like this in therapy, or can they express it quietly or even simply feel these things, without actually acting on them?

For the record, I'm not trying to discredit my therapist. She's actually really great and has been very receptive to me, but this is one issue she is being very stubborn about, and I hope she knows what she's doing. She's also still a trainee, so I don't think how widely she has treated people with BPD before.