When you have a child with another person, you believe that they'll be the parent you believe they can be. You expect them to see your child regularly. Even if you divorce, you (usually) want them to remain in your child's life.
Unfortunately, not all people react to divorce in the same way. Some look at it as a way of avoiding the other party, which can, intentionally or not, impact child custody and visitation.
What should you do if the other parent doesn't show up for visitation time?
First, it's a good idea to do what you can to talk out the problem with the other parent. Not all issues require a court's intervention. Maybe there is a way that you can work together for the better care of your child, even if you don't get along yourselves.
If the exchange is the problem, you may be able to involve a third party. Having a drop-off location would allow your child to be picked up by either person without having to see your ex-spouse. This is sometimes beneficial when parents don't regularly appear for visitation time.
If this doesn't work, then you can look to the courts to enforce visitation. Typically, parents appear due to having trouble getting enough time with their children. A parent who is shirking visitation and custody responsibilities can be taken to court and told to obey the visitation orders. If the parent cannot do so, the judge could decide to alter the parent's visitation rights.
For example, if a parent never comes on time or does not want to see the children, the judge may determine that it's in the children's best interests to see the parent less often or in circumstances where they have no choice, like with a supervised visitation schedule.
Judges can modify custody to a point where one parent gives up their rights completely, but this is usually only common in extreme situations. In most cases, judges do what they can to keep both parents in the lives of their children, unless there is a significant reason not to do so.
As a parent, it is heartbreaking to watch your child suffer, so it is possible to address your concerns with the court if the other parent won't work with you. Your child has to come first, and that may mean adjusting the custody schedule.