Divorce is not yet acknowledged here in the Philippines. Couples will be given two options, though. They can file for a legal separation where in the conjugal properties of both parties will be divided and the married surname of the woman will be dropped but both cannot re-marry again. Or, they can also opt for an annulment which is more like divorce, however, the court process is much longer and pricey. I have a friend who experienced the same fate as your niece. She is now 26 years old, and she once opened up to me that her parents filed an annulment when she was just 10 years old. At her young age, she mentioned that she honestly was not able to understand the real situation quickly. She was crying as she watched her dad pack his stuff and leave their house. Nevertheless, the positive thing was that her parents' decision was a mutual one. They were in good terms until the annulment was approved. This somehow made my friend slowly get through everything. Her parents were constantly taking her out for dates separately and she became fine with the set up. As per my friend, her parents' were patient enough to make her feel that they were not a broken family. It helped her accept the reality that yes, they do not live together, however, they are still a family. Her dad now has a new wife and children, yet, the connection with my friend and her mom was still there. Although there were times where they were not complete during special occasions, her dad would always make up for the lost time. In my own opinion and based from my friend's experience, explanation is just secondary. The parents need to make the child feel that she still has a mom and dad. Of course she will not completely get it though, but it is important to treat her the way that she would understand that even though her parents are not together, she is still blessed because they are always there for her. Make her feel thankful rather than different. Hope this helps! :)
Hi Phil, I'm not in favor of divorce but hope this article helps: https://ph.theasianparent.com/divorce_and_your_kids/