Hi montanesa,
Is there an underlying cause? Yes! Of course! There always is! I'm thankful uBPDh voiced it this time. He's still upset with his parents for not coming to a big concert in which he directed a piece during the intermission. This is something that's been going on for a long time. He's been a musician since he was six but says his parents have only come to three or four concerts of his during his life. However, his parents didn't come because they had to take care of grandma.
So, how on earth would you approach this issue? There's a battle royal between my husband and his parents and I'm sandwiched in the middle. I know it helps me to know the root cause of these blow ups (there's always something else: a concert, etc.) but I am sure his mom is going to think I'm a drama queen and that her son is just like everyone elses' son and that he just needs to grow the Dickens up.
of course there is a storyline to go with every drama. Emotions conjure facts - magical thinking is a sign for BPD.
Can't fix the relationship between the two parties. Getting involved sets up a
KAPMAN triangle and ensures perpetual merry go round.