Walter, every point you make is spot on.
This is part of why I suffer, because my dp has it this easy... My dc love and respect him as a father, he loves them. When we are together we are as a family and probably look like one to outsiders. This has been from the very beginning, he never had to earn it, never had to fight for it, they just accepted him and he them and it was perfect. However...
In his blinkered outlook, he cannot fathom what I go through as his EOW partner, cannot fathom his own failings (out of guilt, over-compensating, etc.). All the things that do his kids and their relationship an injustice, he cannot see the knock-on effect it has on us all. Cannot see how his behaviour leads to the complete opposite to what we have with my dc. I will never have with his kids, what he has with mine. I used to be bitter and challenge every injustice, argue every little hurt. It was making me crazy, wrecking our relationship, because to him, his children are perfect, they can do no wrong. If they are rude or tell him he's a bad father, it is their mother's fault, 'they're under so much pressure!'. Yes, of course, it's not their fault...
I am learning to accept that now with stepping back and detaching. They ain't my kids, they don't want a relationship with me. It's fine. My primary responsiblity is to my dp/our relationship and my dc.
OP - get the books and make your dp read them too! x