Elegy, a song expressive of sustained earnest yearning, or mild sorrow after loss.

ELEGY, n. A composition in verse, in which, without employing any of
the methods of humor, the writer aims to produce in the reader's mind
the dampest kind of dejection. The most famous English example begins
somewhat like this:

The cur foretells the knell of parting day;
The loafing herd winds slowly o'er the lea;
The wise man homeward plods; I only stay
To fiddle-faddle in a minor key.