So glad you posted! I'll come back soon to check on your response!
Well...the answer to your question is "it depends".
Do you want a relationship with BPD "in it"? I would encourage you to "accept" that choosing a relationship with him equals choosing a relationship with a person that acts in ways consistent with BPD.
Please don't read any good or bad judgment in that statement. More of a statement like "If you choose to walk in the rain, don't be surprised to get wet."
Thoughts?
Best,
FF