C.S. Lewis, Mere Christianity

The Christian attitude does not mean that there is anything wrong about sexual pleasure, any more than about the pleasure of eating. It means that you must not isolate that pleasure and try to get it by itself, any more than you ought to try to get the pleasures of taste without swallowing and digesting, by chewing things and spitting them out again.

[Book III, Chapter 6, "Christian Marriage"]

Giovanni Giacomo Casanova

Marriage is the tomb of love.

Captain Corelli's Mandolin

When you fall in love, it is like temporary madness. It erupts like an earthquake and then it subsides. And when it subsides, you have to make a decision. You have to work out whether your roots have become so entwined together that it is inconceivable that you should ever part. Because this is what love is.
Love is not breathlessness, it is not excitement, it is not the desire to mate every second of the day, it is not lying awake at night imagining that he is kissing every part of your body. . . . That is just being in love, which any of us can convince ourselves we are. Love itself is what is left over when being in love has burned away. It doesn't sound very exciting . . . but it is.

G.K. Chesterton, Orthodoxy

I could never mix in the common murmur of that rising generation against monogamy, because no restriction on sex seemed so odd and unexpected as sex itself. . . . Keeping to one woman is a small price to pay for so much as seeing one woman. To complain that I could only be married once was like complaining that I had only been born once. It was incommensurate with the terrible excitement of which one was talking. It showed, not an exaggerated sensibility to sex, but a curious insensibility to it. A man is a fool who complains that he cannot enter Eden by five gates at once.
[Chapter IV, "The Ethics of Elfland"]