I believe, and think it is fair to say based on my history, that I became dependent on therapy, and for me it was the idea of therapy more than the therapist per se. But that's because I think I had OCPD. I was diagnosed with PDNOS 10 years ago, but that's after I had fallen apart. Never diagnosed with BPD.
There are some theories out there, and they make sense to me, that all people with PD's lack a strong, consistent sense of self. And that's part of what made me vulnerable, I think, to becoming enamored with, addicted to, and dependent on the idea of therapy -- both as part of my identity (a"mental patient") and as my (unrealistic?) hope as a way to become an OK, better person.
I also believe It's fair to say that the therapy establishment encouraged the idea of trust and dependence on the therapists, not recognizing situations like mine where that would be a bad idea.

nor did I recognize it, because of the absence of a good sense of self.