BPD + mono = ???
My partner also has BPD and, in the past, has needed monogamy.
To answer Newtoday's question, at least from my experience, choosing to
be monogamous was a mistake for me. To me, it DOES feel like an orientation of sorts and while I'm very good at keeping to relationship contracts (or requesting changes if needed before acting against them) it did seem limiting and unsatisfying to be monogamous with him.
Now that he's a year into DBT (Dialectical Behavior Therapy) with a qualified team of therapists, a LOT has changed and he has now opened up to polyamory. His issues around perceived abandonment haven't magically disappeared but we both understand better how to address them and deal with them when they pop up.
I want to be clear that there is NO WAY that I could be maintaining this extremely difficult relationship if he were not 100% on board with his therapy and personal work. That's not to say he doesn't relapse but the structure of our relationship includes him holding himself accountable as he is able (more every month).
That rollercoaster can get old. Yet, I am so grateful for our whole complicated history- I've learned so much about myself and my own needs, boundaries, etc.
That take home for me? Prioritize yourself, make sure that you're getting what you NEED (and at least some of what you WANT) before comitting to the long haul. My relationship with my partner, because of his BPD in the context of him working on it, has given me MUCH more than it has taken out of me. If it were the other way, I don't think I'd still be able to be with him.
Good luck to you and PLEASE make sure that you both have proper therapy with folks who are trained in using DBT for BPD (preferably only one generation from Marcha Linaehan in training)