C. S. Lewis on 'Being in Love'

The trouble arises when poets and others set up this good thing as an absolute. Which many do. An innocent and well-intentioned emphasis on the importance of being-in-love with one's spouse (i.e. its superiority over lust or ambition as a basis for marriage) is in fact widely twisted into the doctrine that only being-in-love sanctifies marriage and that therefore as soon as you are tired of your spouse you get a divorce.

Thus the overpraising of a finite good, the pretense that it is absolute, defeats itself and corrupts the very good it set out to exalt, reducing marriage to mere concubinage.

Treat 'Love' as a god and you in fact make it a fiend.

--a 1942 letter to Daphne Harwood, in The Collected Letters of C. S. Lewis, Volume 2 (Cambridge: Cambridge University Press, 2004), 511