Is there some rule that says you can't get engaged while still married?

You broke up with your wife 2 years ago. You're on the path toward divorce. The legalities aren't tied up. Can't you promise to marry the new woman in your life? What's the morality problem— beyond the basic moral problem of divorce?

Looking at the pictures of Dinesh D'Sousa and Denise Joseph, I can't help suspecting that some people are bridling at the difference in age, beauty, and — perhaps — race.