Here’s another excellent video from Fr. Robert Barron on how a relationship will only endure when two people fall in love, not so much with each other, but together with a “transcendent third.” Relating that to Christian marriage he says

To get married in the Church, that is to say, before God, what you’re saying is, “we’ve discerned that together we are in love with God and we’ve discerned that God…has drawn us together. It’s not just, the two of us met…the two of us fell in love. It’s something…more mysterious than that. It’s that God for his purposes has drawn us together, that we might find our salvation in each other’s presence and that together we might fulfill a common mission.”