I know, this is hardly revolutionary or unique advice, but I was recently asked about this issue by a young Catholic man who called my "Open Line" radio show (heard every Thursday at 3:00 p.m. ET). He had been dating a devoutly Presbyterian girl, and her father didn't like it one bit that the guy was Catholic.
I think my response to his "what do I do now?" question may have surprise him. (It apparently surprised and even dismayed a few of my listeners, judging from some of the e-mails that came in after that show.)
My basic premise, which I advert to in this audio segment is that, more often than not, mixed marriages (i.e., when a Catholic marries a non-Catholic) are a recipe for serious problems down the road in that marriage. My advice to Catholic parents is, teach your children well the importance of finding a devoutly Catholic spouse. Eventually, if you haven't taught them this maxim and they, as a result, do not act on it, you will very likely see problems springing up in your extended family due to your sons and daughters being, in a certain sense, unequally yoked with non-Catholics. Word to the wise.