Marriage gives love the structure, the shelteredness, the climate in which it alone can grow.  Marriage teaches spouses humility and makes them realize that the human person is a very poor lover. Much as we long to love and to be loved, we repeatedly fall short and desparately need help. We must bind ourselves through sacred vows so that the bond will grant our love the strength necessary to face the tempest-tossed sea of our human condition.

-Alice Von Hildebrand in the foreward of her husband's book: 
Marriage: the Mystery of Faithful Love