Made for a Dutch trivia show
to illustrate an upcoming question, the jist
is that Richard Wagner
has the hots for Matilde Wesendonk but she's married to this business man and art lover,
Otto Wesendonk.
Their correspondence can't be more than platonic
so as deliriously happy as he is, it hurts him just as much.
In one of the opera's from
his Nibelungen-trilogy he writes the letters GSM over the notes,
meaning "God Bless Matilde" (Gott Segnet Matilde).
This opera premiered in 1870, and the name is "Die Walkure".