One interesting C. S. Lewis quotation caught my eye this evening, after someone had asked about the difference between loving someone and being in love:
What we call “being in love” is a glorious state, and, in several ways, good for us. It helps to make us generous and courageous, it opens our eyes not only to the beauty of the beloved but to all beauty. Being in love is a good thing, but it is not the best thing. It is a noble feeling, but it is still a feeling.
The promise of marriage, made when I am in love, commits me to being true even if I cease to be in love. A promise must be about things that I can do, about actions: no one can promise to go on feeling in a certain way He might as well promise never to have a headache or always to feel hungry.
Knowledge can last, principles can last, habits can last; but feelings come and go. But, of course, ceasing to be “in love” need not mean ceasing to love. Love in this second sense — love as distinct from “being in love” — is not merely a feeling. It is a deep unity, maintained by the will and deliberately strengthened by habit; reinforced by (in Christian marriages) 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 the promise.
It is on this love that the engine of marriage is run being in love was the explosion that started it.