When can a child decide not to visit the other parent?

The child can decide the moment he/she turns 18.

If the current visitation plan does not work, then it needs to be modified.

If one parent is harming the child (physically abusing, not feeding, calling bad names, etc.) you will need proof.

You need witnesses with personal knowledge. What is personal knowledge? Briefly, the person can only testify to what they personally experienced - heard it, saw it, tasted it, smelled it, etc.

So if the child came home with bruises, the neighbor can testify to the bruising but not what the child said about how the bruises got on his/her body.

School teachers make excellent witnesses because they are impartial and only want what is best for the child.

School records are presumed accurate. So if there are many tardies on the days the other parent has the child or many unexcused absences when the parent has the child, that is powerful evidence. If the child comes to school dirty, tired, stressed, unprepared only on the week-ends when they visit the other parent, you have some powerful information for the Judge to hear.

A professional mental health expert that is willing to testify in court is also powerful.

If things are bad and you need some more evidence, then asking the Court to appoint an amicus attorney to meet with the parents, child, people with personal knowledge and review doctor and school records might be the way to go.