Do you deny that it is sometimes morally better to get divorced since, in the long run, it would be better for your children's emotional and maybe physical well being?
No.
If you don't deny this then the divource rate has no bearing unless you evaluate each case to determine if the children are better of or not.
I disagree. It is well established both anecdotally and scientifically that
in general children from broken homes do less well at school and suffer more behavioural problems. Therefor a rising divorce rate is a problem.
But children are not the only problem with a rising divorce rate, although they are the only one I would consider Moral, as opposed to practical.