What did your girlfriend say about poly relationships? Maybe you can have an “open” relationship, where you can have one main girlfriend (the girl you are with now) and then people that are kinda side-lined. Find out what works with you. I think you should be honest with your girlfriend though (because if she finds out another way things will be 1000x worse). Maybe it’s the long distance part that doesn’t work? I don’t know. Sit down with yourself and see what isn’t working for you. Maybe it’s just your BPD that is affecting you, that you can’t get you close to your girlfriend and so you have feeling for other people so you can distance yourself. Or maybe it really is monogamy that isn’t working for you, and trying you being a “square” peg fitting into a “round” hole isn’t working for you.

Don’t feel like a monster though. I’ve had relationships where I was talking with other guys because I wasn’t getting what I needed from my relationship. To me, it was the attention that I craved, the “petting of my ego” so to speak. It seems to be different with you, though. I just hope that when you are wanting to go into a polygamous relationship it’s not for the wrong reasons.
Best regards,
Chelsea.