Many ‘children’ grow up with a need to abuse their parents. Maybe they had some traumatic childhood event, maybe it was just a divorce, maybe it is a way to divert failure, etc.
They leave childhood and one assumes that they will grow up. After all they are eighteen, twenty eight, forty eight…. when do they let go of the fact they didn’t get to go to the zoo?
By this time, many parents, having tried when the child was eight and fourteen and eighteen and twenty five and thirty three, tend to give up.
Tired of playing a role in their fantasy, the parent (s) go on to live their own lives, not wanting the drama.
The fact that explodes at some point is that the ‘child’ is trying to play them. It is not that they want a relationship with the parent, they want to manoeuvre the parent(s) into a position where they can hurt them.
For some reason hurting the parent is important.