Why do some couples who are not happy wait until the children are grown to split?

It doesn't seem right to me either but I understand where they are coming from. They are trying to give their children a chance to grow up in a family with both parents under the same roof. I'd say that's admirable as long as they are not fighting in front of the children and making them wish if their parents were divorced, and as long as they are not taking their frustration out on their children.