BPDFamily.com

I met the guy I wanted to marry. He was perfect. A month later I found out he had BPD. I don't want to break up with him because of that necessarily, but I know he hasn't always told me the truth about things. He gets very moody when things don't go his way, and he never takes responsibility for his own mistakes or emotions. I don't want to hurt him. I love him, but I can't stay in this relationship. I need to break up with him but he's going to ask me why. Heartbreak is a big deal to him, and since he doesn't know he has BPD I don't know what to say because you should tell them that they have it if they don't know. And yet I don't want to lie to him and give a false reason for leaving. Advice?

Sorry your are having these hard choices.
If the relationship is new, you really have nothing to lose by doing or saying anything in the process of ending a relationship.   If there are no kids, shared assets, living arrangements, or your safety involved you can pretty much end it on your terms.  You can do it unilaterally and honestly, or deceitful. I might choose honestly if it were me.  You should be absolutely clear and positive and eradicate any illusion of second chances.  I've observed that pwBPD hear things the way they want to hear them.  So, you may have to rephrase and stick with it.
I know being in love feels good, and being a naturally good and nice person makes breaking up feel cruel or insensitive.  However, an example I use is that if you find that you have boarded the incorrect train on your journey, you must get off the train and change tracks, because you cannot change where the train is going.

Except that there is a human being on the other end who will be very hurt... .in the case of BPD, where rejection sensitivity is very high, hurt more than others.

I left a relationship of someone I loved. I think it is not so much a matter of accurately disclosing your reasons for leaving, but more a matter of releasing with grace and dignity.

This author of this article ( https://bpdfamily.com/bpdresources/nk_a125.htm ) suggests going through a step-wise series of being disinterested and increasingly distant. When the partner has the typical reaction to pull you back in, you say "its nothing, there is nobody else", but stay the course. After a few weeks of this, the partner will be start to drift from a rejection reflex to a defensive reflex (I deserve better). You can then do a trial separation or say you need some space or say "you're wonderful but I'm not feeling it". If he over-pursues at any point, tell him he is pushing you away and ask for space. The idea is to invest a few weeks (no more) and back off in increasing stages of carelessness (but not disrespect or maliciousness). It won't hurt as much.

In my own thinking, the way people get damaged in breakups are 1) if the are betrayed (dumped for someone else), 2) ghosted (this is horrific), or 3) the relationship is terminated for personal defect (BPD, has a child, doesn't make enough money, too short, didn't go to college, etc.).

You've been going out a month?

Whilst I like Skip's breakup method, it really appliis to longer relationships. I would think MANY relationships breakup after a month - so I'm not sure such a structured drawn out breakup is required.

Understanding of course that he has BPD, which means you do need to treat him more kindly than others. But I think it is quite OK to say "I just don't see us going anywhere", or "I just don't think I feel that way about you". Be prepared for him to try to question you, to make you justify yourself, to give him another chance - ANYTHING to keep you. You need to stay your ground. DON'T get into a defending, justifying arguement. You do NOT need to actually provide him any reasons. Just keep saying the same thing in response to anything he says: "True/Maybe - but I want to breakup".

Agreed.