BPD is a far more intricate issue than online materials and books suggest. Most people have grown a stigmatized view of Borderline Personality Disorder, because literature that most of us have been exposed to, makes these people out to be monsters! Fact: The run of the mill Borderline, is definitely NOT.
A lot of people with BPD will give ya the shirt off their back, if they perceive you're in need. Many are appropriately dual-diagnosed as being Codependent (over-giving, people-pleasing, fixing, rescuing and repairing others). We see this duality most profoundly, among people in the 'helping' professions: Psychotherapists, psychologists and psychiatrists, doctors, nurses, surgeons and the like.
The key element that exists among ALL people with BPD traits is fear of closeness and intimacy. In short, they're afraid to attach fully, for fear of disappointment and/or emotional annihilation should they lose you. This fear extends even to their own children: "If I let myself love this child as much as I want to, and something happens to take him/her away from me, I won't be able to live thru it!"
Attachment fears are so very prevalent, because 85 - 90% of us didn't get the quality of mothering we needed, as newborns onward. This set us up to feel fear, trepidation and distrust in another, when an opportunity arises to bond with them. How could it not?!
Imagine a tender little soul who has bonded with his mother while gestating in her womb, coming out into a much brighter, colder world, and not being able to feel an intrinsic and warm sense of connection with the woman who gave birth to him.
What is that infant to think? Is he able to accept that he's lovable and good enough, when his Mommy can't or won't return his adoration? Will he somehow as he grows, be ABLE to convince himself he is worthy of someone's undying devotion and love?
I think not. And this my friends, is why Borderline Personality Disorder exists. Few of these people are tyrants. Most are just broken hearted souls, who never got the love they needed, to make them feel safe to ATTACH.
You cannot change this tragic flaw in a Borderline, no matter HOW much you love em, and endlessly try to prove it. Hell, most psycho-therapists can't even begin to repair this damage!
But if someone with attachment fears is lucky enough to find a professional who can help them begin to see themselves as WORTHY of real love by building high regard for the Self, along with growing their emotional repertoire, there might be a shot at becoming whole and well~ and in My not-so-humble view, that's priceless!