Things I've heard from my gfwBPD, usually when I'm trying to keep calm when being accused of de-prioritizing her:

"If you're not giving me attention, then I can find it somewhere else."  
"You weren't paying attention to me, so why shouldn't I talk to someone else? It's just going out to dinner."  
"It's obvious you don't care about me; you don't even react when I tell you that other people want to pay attention to me."  
"You keep telling me that I'm a priority, but I don't see it in your actions. I don't know what you're really feeling."

Is that really what someone with BPD wants? Constant attention, even if I lost my cool and raised my voice? I can't do that, nor can I give that much attention, period. She'll say "all I need is a compliment" or "I just want to know you notice me," but those aren't cheap requests. They're not just words. I know what it feels like to need some reassurance, but not on an hourly basis! I can understand how hurtful it could feel to not get that kind of reassurance from your partner, but there's a limit. She says that there's nothing wrong with wanting attention, and I would agree with her, but up to a point. At want point does needing attention become unhealthy? It would take me a long time of neglect before I felt starved for attention, and even then, I don't start seeking it elsewhere. But for her, she feels starved after only a day or two, sometimes less.

Is that all she wants? Is that all I am? Just a body that gives her attention that can be swapped out for another person? How do I tell her that she's valid without 1) needing constant attention and 2) guilting me into giving it? Why does she need that much attention?