We already do something very similar with conceal to carry laws. Some states offer reciprocity, some don't. Some states make it hard to get them and other don't. States are free to determine which licenses they accept. The same could be done with marriage laws. Accept some licenses and not reciprocate others. It's not like a contract law, it is a state license and could be resolved by the states at their level. Just as in cases of taxation, don't like your states laws? Move.