I think it's 50/50. A person with BPD probably doesn't change partly because they can't pinpoint what they're doing wrong in their relationships and partly because they feel their behavior is adaptive (i.e. it helps them feel more important, get more attention, quell their fear of abandonment, or generally feel more secure in a relationship).

Change is hard. I think we all feel like changing could cause new problems. That's why habits stick so well. We fall into the same patterns of thought over and over again. The only difference between the average person and the person with BPD is that the BPs world is unstable if they don't change.