Scripture tells us that the unbelieving spouse is made holy through the believing spouse (1 Cor. Sacramentally in marriage the spouses are the conduits of grace to each other and in a mixed-marriage of disparity of cult the Catholic is a conduit of grace to the non-believer.
If this leads to a free conversion of belief by the non-believer then the church rejoices.
If a Catholic insists on marriage to a non-Catholic, the Church allows it, but wants to protect the soul of the Catholic in the marriage by making sure the non-Catholic understands the moral teaching and obligations of the Catholic party and assure that the Catholic is not in a position hostile to his or her faith. In the above example the two people are baptized Christians of different confessions (or denominations), but a non-baptized person is not a part of the Christian family.
One of the reasons that the Church exists is to safeguard the souls of those in its care.
I’ve seen this question come up in the Catholic Match forums and many people, speaking from past experiences, agree that they would not do it.
But what if someone you’re interested in is a recent, or soon-to-be Catholic convert?
There are couples who are devout, who seek holiness through the sacrament of matrimony, and live in such a way to witness to the life and love of Christ.
So what do you do if you find yourself interested in or dating a non-Catholic? Remember that your situation may be different than somebody else’s, so consider them in prayer. Your non-Catholic boyfriend or girlfriend needs to love you for your faith, not in spite of it.