"Being in love is a good thing, but it is not the best thing. There are many things below it, but there are also things above it. You cannot make it the basis of a whole life. It is a noble feeling, but it is still a feeling. Now no feeling can be relied on to last in its full intensity, or even to last at all. . .In fact, the state of being in love usually does not last. . .But of course ceasing to be 'in love' need not mean ceasing to love. Love. . .is a deep unity, maintained by the will and deliberately strengthened by habit;reinforced by the grace which both partners ask and receive from God. . .'Being in love' first moved them to promise fidelity: this quieter love enables them to keep their promise. It is on this love that the engine of marriage is run: being in love was the explosion that started it."

[C.S. Lewis, Mere Christianity ]