Consider a pretty ordinary scene with a person with borderline personality disorder: they say “I hate you! You’re going to leave me!”
The natural response is, of course, to respond with “I don’t hate you, and I’m not going to leave you. I love you very much and I want to be with you.”
Don’t do that.
Instead, say something like “you must feel really scared– I’d feel scared too if I thought someone I loved was going to leave me.”
Now, you might think that this is going to make the borderline feel worse. After all, you just said it was okay for them to be scared! Instead of showing them that their feeling is silly, you implied that it made sense!
But, in reality, if you say the first thing, what goes through a lot of borderlines’ minds is something like this: “They’re just saying that! They don’t really mean it! It’s not true! Oh no, I’m not supposed to be feeling this way, I’m supposed to not worry that they’re leaving me, I am the worst person in the whole entire world, and I know they’re going to leave me because anyone would leave the worst person in the world!” And then they start sobbing and you have no idea what you did wrong.
If you say the second thing, what goes through a lot of borderlines’ minds is something like this: “oh! They really get it! They must really care about me if they get it. And it’s okay to be scared– they said that it was, after all. Oh, huh, I guess I feel better now.”
Borderlines want to feel understood. We often feel like our emotions are unacceptable or bad, which just makes them more intense. And we often have a hard time figuring out what we’re feeling at all. All of these things can be helped by a simple process of (a) figuring out something, anything, that makes sense about what the person with borderline personality disorder is doing and (b) saying it.
If they’re mad about something you did that was, in fact, kind of a dick move, say that it was a dick move. If they really did make a mistake, say “it’s okay to feel bad that you broke the dish.”
It’s important not to say that things are true when they actually aren’t. Responding to “you hate me and you want to leave me!” with “yes, I do” is not going to improve the situation.
Of course, sometimes this is very difficult. As Topher said when I originally explained this concept to him, “but most of the time I DON’T understand your emotions and they DON’T make any sense!” One thing you can do is look for aspects of the situation that make sense. Maybe it doesn’t make any sense at all that the borderline has come to the conclusion that you’re a robot, but her distress at the possibility makes perfect sense. Or maybe the fact that the borderline is curled in the fetal position crying because she got an 89 on a test doesn’t make very much sense, but feeling sad about it certainly does.
It can also be helpful to prepare a few safe scripts for situations where you don’t understand what’s going on at all. It is almost always safe to say that the borderline is in a lot of pain or doing something really hard, on account of this is true of borderlines approximately 90% of the time (and nearly 100% when they’re telling people that those people hate them). Similarly, “that sucks” or “you must feel overwhelmed” or “you seem sad/angry/afraid [choose your borderline’s favorite emotion]” are often great. Do mix up your scripts, though; if they catch on that you say “that sounds hard” every time, then it will stop working.
I’m not saying that this strategy works for every borderline. But it works for a lot, and it’s worth a shot.