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, and it subordinates (especially at first) our merely animal sexuality; in that sense, love is the great conqueror of lust. No one in his senses would deny that being in love is far better than either common sensuality or cold self-centredness. But, as I said before, ‘the most dangerous thing you can do is to take any one impulse of our own nature and set it up as the thing you ought to follow at all costs’. 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. Knowledge can last, principles can last, habits can last; but feelings come and go. And in fact, whatever people say, the state called ‘being in love’ usually does not last.
—from Mere Christianity