Samuel Taylor Coleridge Quote

Alas! they had been friends in youth;
But whispering tongues can poison truth,
And constancy lives in realms above;
And life is thorny; and youth is vain;
And to be wroth with one we love
Doth work like madness in the brain.

Part II, l. 408 - Christabel (written 1797-1801, published 1816)