Bluebicycle, there is this tendency with some people to develop a personality to match our BP (a personality to make get us nearer the "psychotic spectrum" (PS) borderline; or just BPD). It protects us by giving us a (more or less dysfunctional, at first) way of expression and also by us feeling anxious when we get too involved (fancies, not necessarily or only tentatively romantic, can be strong in a delusional mind, as you may know). Like with every unease and our perfect (sarcasm) way of expression, we may sabotage the emotional bond.

That she visits BP support groups is probably enough indication that she has accepted and wants to work on her problems, the one sketched just now (and by you) included. She probably already found better ways of expression and less assertiveness. Going to a BP support group means you have to leave your façade of (over)confidence, typical of those with personalities to match, at the door. She's probably done that.

You might still be a bit careful not to become too close with people that still have borderline personality problems. We are very nice, but may not always look the part, personality-wise. Some personalities just don't mix very well with other, specific personalities.

You'll do fine!

Edit:
We mean you no harm.

Always wanted to say that!