The close call that
Frederic Chopin had with tuberculosis in 1835 ended his engagement to Maria, thanks to her mother. Fred put the letters from Maria and her mother into an envelope on which he wrote “My sorrow”.
From this experience came a waltz that ended up in the desk drawer, but shouldn’t have. He wrote it the last day he saw Maria.
Chopin: Waltz in A-flat, Op. 69/1 (“Farewell Waltz”)