Only the rarest good fortune brings together the man and woman who are really as it were ‘destined’ for one another, and capable of a very great and splendid love. The idea still dazzles us, catches us by the throat: poems and stories in multitudes have been written on the theme, more, probably, than the total of such loves in real life (yet the greatest of these tales do not tell of the happy marriage of such great lovers, but of their tragic separation; as if even in this sphere the truly great and splendid in this fallen world is more nearly achieved by ‘failure’ and suffering). In such great inevitable love, often love at first sight, we catch a vision, I suppose, of marriage as it should have been in an unfallen world. In this fallen world we have as our only guides, prudence, wisdom (rare in youth, too late in age), a clean heart, and fidelity of will...'
-- J.R.R Tolkien, Letters, 51-52