BPD is characterized with a loose sense of sense. This translates to radical changes in the way pwBPDs behave around others known as the "Chameleon effect".
I got to see sides of my ex SO that are amplified with her new friends around and her recent life choices that I really dislike, mostly around triangulation and poly-romantic/sexual relationships. I find myself really disappointed and angry at her, but thinking about this logically - it's absolutely NONE OF MY BUSINESS! Who am I to expect anything from her? She doesn't owe me anything and it's really her life and her choices that she needs to live with.
So I asked myself what am I really angry about, what is the source of my disappointment?
Does this come only from caring for her and loving her, or is there something beyond that?
My insight that I wanted to share here is that I'm angry at her for not living up to MY fantasy of her.
It's funny because it seems childish and somewhat selfish but I'm glad it's something in me I can work on
