Why do some women stop men from seeing their kids?

It can be anger, punishment, jealousy, wanting to protect the child etc. The reasons differ from case to case but this is where the law comes in and protects the child's right to both parents. None of the parents can go against a court ordered visitation or custody. And there seems to be a misunderstanding that visitation is something you only get if you can pay child support, as a reward or something. This is not true and the issues are two different ones when addressing them in court.