2386 It can happen that one of the spouses is the innocent victim of a divorce decreed by civil law; this spouse therefore has not contravened the moral law. There is a considerable difference between a spouse who has sincerely tried to be faithful to the sacrament of marriage and is unjustly abandoned, and one who through his own grave fault destroys a canonically valid marriage
Suppose the unbaptized spouse in a canonically valid marriage “unjustly abandons” the baptized spouse and destroys the marriage? Would these be clear grounds for an annulment?
Problem #1 of course being, why is a Catholic marrying an unbaptized person in the first place.