Your children need both parents for their well-being
There is a particularly insidious belief that fathers somehow play a less critical role in the development and mental health of children than mothers do. There is often a cultural bias that expects parenting work from mothers but not fathers. For some time, that may have led to the courts preferring to place children with one parent instead of creating shared custody scenarios.
However, research on the mental and social development of children from divorced families makes it clear that both parents play an important role in the health of the family. That doesn't mean that unhappily married couples should stay married for the kids. Witnessing ongoing conflict could be as damaging as a divorce. Instead, it simply means that both parents need to play an active role in the lives of the children after divorce.
Being part of their lives protects them from feelings of abandonment
Divorce usually results from conflict between the parents, not issues with the children. However, kids are very quick to place the blame for the dissolution of their parents' marriage on themselves. It is common for children of divorcing parents to experience both guilt and extreme fear of abandonment.
If one parent doesn't receive adequate parenting time, this could have repercussions that impact the children. Specifically, the kids may feel as though one of their parents chose to abandon them, which can be a damaging emotion.
Your children may worry about losing the bond that they share with you or simply no longer being an important part of your life. Even children who wind up alienated from one parent by the actions of the other may still experience feelings of abandonment related to the parent not present in their life.
2 parents can provide better resources and support
Parenting is a difficult and challenging job in the best of circumstances. For couples who divorce and must then share custody, parenting can be much more difficult than it is for other families. Your children will have unique emotional and social needs during and after the divorce.
Having emotional support from both parents, as well as time with both parents can help children process the issues they have related to the divorce and other problematic experiences. Maintaining a relationship with your children often means asserting your rights as a parent.
If your ex seems to want to cut you out of the lives of your children, you may have to take forceful and assertive action to protect your parental rights. However, you also need to stay focused on what is best for the children and avoid either talking poorly about your ex in front of them or otherwise damaging the other parental relationship.