Courts have distinguished between marital fault and misconduct that would lead a court to find that a parent is unfit. This means that proving that a parent was a horrible spouse does not mean that the court will also found that the parent is unfit. Of course, there is a difference between seeking custody versus eliminating parenting time. To eliminate parenting time, some courts take the view that children are only entitled to D- parents, not A+ parents. However, when it comes to custody, the court will generally determine which parent is better.
Furthermore, all cases are fact sensitive. So, arguing that a parent engaged in adultery may have absolutely no impact on a custody or parenting time award in New Jersey. However, if one of the parents is bringing the child around the new paramour, the court may side with the other parent as courts do not like to have children be subject to new paramours, especially right after the parents separated or divorced.