Even before divorce, the lives of children of divorced parents may differ substantially from children in intact families, and it is plausible that these differences, rather than parental divorce, are the source of child mental-health problems.
If you look at divorce as a process in that you study the differences before, during and after divorce, it turns out the most harmful effects happen before the divorce even occurs.
These kids are already much sadder, and they get sadder yet when the parents go through the divorce.
