Hi
TiredofBeingAfraid,
That's a great question. It does say a lot that your fiance's brother acknowledges that he has a problem--that is a tough thing for him to do. At the same time, unless he really works on himself, he's unlikely to change.
He reverts back to child like behavior like going into our room and slamming the door behind him, or just getting into bed and throwing the blanket up over his head and whining like a five year old would do.
I realize this is probably how he would cope with problems when he was a child, but he's almost 30, and this needs to stop. When he does by some miracle answer me about it, he uses words like bad, sad, and mad to describe how he's feeling, but not much else.
It sounds like he's very emotionally immature and also needs constant validation. There are some good suggestions in this article:
Communication using validation. What it is; how to do it. Although I know it can be tough to do, you're doing the right thing by asking him to explain how he feels and validating his feelings.
This has to be tough on your fiance, but he's very lucky to have an understanding fiancee. He may just not be ready to talk about it. He may also feel like no one understands what he's going through (it can be very isolating having a relative with BPD). He's always welcome to join this site too--there are a number of members here with siblings with BPD.