Parental alienation, turning the children against the other parent. It’s psychological abuse of the children.
What the father does, and what the mother does in these instances are two different things. Protective services are trained to protect women, and woman can get away with a hell of a lot. If a man did some of the things they do, he’d have the book thrown at him.
When I went through one of my divorces, I tried to communicate problems with protective services. They took this to be hostility on my part. They didn’t want to hear from me at all.
I’m not sure if this is the norm or not, but I suspect it’s a lot closer than I would like to think.