Does the bs get to big for them or wht?
My guess is that because of the extreme core inadequacy and intense self-loathing and self-disgust they carry with them, they cannot anyone who exhibits qualities that reflect how they feel inside. When my ex said horrible things about someone else, it was sheer projection, a crude defense mechanism that allows him to bounce out the feelings he cannot resolve within.
When your ex and father devalue people for not meeting expectations, they are describing their own inner thought processes about themselves and their inadequacy.
You see this clear as day with parental alienation, where the alienating parent projects abuse and neglect on the target parent. It's a way to get rid of the bad feelings, and that's all they've ever learned to do, so it's real to them. They can no easier understand how we see things as vice versa. People with BPD cannot process grief and other difficult, negative feelings, they use these other methods like projection, devaluating others, splitting, etc. It's a big tragic maladaptive bunch of coping mechanisms that don't help build healthy intimate relationships. It's never their fault.
