Hi ChrisE-
And welcome! I'm sorry you're experiencing that, the unpredictability and instability can be crazymaking.
Do BPD partners have no empathy?
Borderlines can empathize well, although a borderline also feels emotions intensely, so intensely that they become the fact, the reality, and that changes with the emotion. And the emotions are "triggered", as it's termed, by intimacy, so the closer you get the more it seems to happen. You sound like you noticed.
So what's the goal? If you want to continue a relationship with her it will be helpful to read and post a lot here, learn a bunch about the disorder, and also learn the tools that those in relationships with borderlines use to function in and navigate the relationship.
You're not alone, we understand, and take care!