The traditional fault ground, and the one used most often in granting divorces, is adultery.
Moral fitness can be more than just one party committing adultery.
You would surely want the court to know if your spouse was an alcoholic or had a violent temper. Similarly, it is relevant to let the court know that your spouse or his or her friends are habitual users of drugs. The mental and physical health of the parties involved While it should be clear that the court will not award custody to a known insane or comatose person, the lesser degrees of physical and mental incapacity can cause problems. If you seriously believe that your spouse has a recognizable emotional disorder or a physical problem that would affect his or her ability to take care of your child, you should see about petitioning the court for an examination. But watch out if you have a history of instability or physical problems yourself.