Narcissistic individuals (which includes Borderlines, of course) tend to globalize their behaviors, reactions to you and their experiences of life in general.
If you have a negative response to them (which may be wholly intuitive or organic, or simply a remnant from a past-life experience with their soul) they presume you are with EVERYONE the way they perceive you to be, with them. God forbid, THEY feel singled-out for your disdain~ you're "surely this way with ALL who encounter you." This is a defense against the shame response in Borderlines, which is triggered if you respond to them less than positively.
Their subjective reaction to you (whether real OR imagined) often spawns name-calling and/or verbal assaults on your character, integrity or professionalism. Borderlines with Queen traits try to shame you. Those with BPD Waif traits will most often try to guilt you into bending to their desires, or simply staying engaged in battle. These mental maneuvers are reflexive and automatic for people with BPD features! It's how they've learned to navigate in life, and survive.
If you lack solid ego strength and a healthy, powerful sense of Self, you'll WASTE a lot of time and energy on these folks, trying to convince them you're not who they think or accuse you of being, and defending yourself. Take it from me: DON'T BOTHER.
Given the BPD individual typically thrives on conflict (because it feels activating to ‘em), trying to convince them (to any degree) their perceptions of you are NOT universal, and are usually inaccurate, creates an endless cycle of circling the drain with them. This is stimulating and enlivening for them, but utterly frustrating (IF you give into it) and exhausting for You!
If you're with a borderline disordered partner, you have SERIOUS self-esteem issues, which have you routinely trying to redeem yourself in Their eyes, after every tiny disappointment or disagreement that might arise between you. In short, if you POSSESSED a healthy sense of Self-worth, you wouldn't choose to be with an impaired individual, in the first place!
People who couple with Borderlines are no healthier than their BPD partners, because in terms of emotional development, they both vibrate at precisely the same frequency. Like attracts like, and birds of a feather flock together. You'll never, for instance, see a bald eagle flying with a swarm of parrots or swallows.