What kind of abuse did ya'll put up with?
It varies since people with BPD traits (pwBPD) are just like us, no two are exactly alike. Also, the scenarios are different from person to person, some are BF/GF, others are engaged, others are married, others have children together, etc.
But one common thread is that it generally worsens over time. It's been compared to the boiling frog analogy. Drop a frog into a pot of really hot water and it will hop out. Drop a frog into water and gradually warm it, you'll soon have a boiled frog.
It's almost as though the other, once the initial adoration or infatuation is past, "lets down their hair" so to speak and you see what's underneath. Then once you seem to have reached your limit, then it lessens for a while and then it resurges again, to a new level, the push-pull repeating.
Then, too, it is more likely for there to be ultimatums and demands, shouting matches, ragefests, unreasonable guilting, disrespect and so much more. It may not be abusive at first, but with some people verbal and physical abuse are real risks.
In my case, I believe it was my spouse's childhood FOO, especially the abusive stepfather but also the complicit mother too. I didn't realize it at first, though just before the wedding I formed an impression I was saving her. In the first decade I thought her episodes were the result of child abuse, but the pattern, looking back, was that her behavior and ragefests gradually worsened.
About that time I got that idea that if we had a child then she'd be happier watching our child discover the joys of life. I was so clueless! It made everything worse because when we divorced, we didn't just have to end the marriage, we also had to deal with the added complication of custody and parenting issues. Our child was 3 when we separated, it took several years in and out of family court before we had a court order that worked. Some 15 years later our child aged out of the system and the parenting issues lessened, but conflict is still there lurking in the background since my ex is prone to being easily triggered.
If you decide your relationship would be unworkable, even damaging, in a future together, better to cut your losses sooner than later. That's not what any of us want, we want all roses and popsicles, but it's the reality when BPD is in the mix.