Tristan's death seems to be the epitome of the tragic dimension reversing into the comic one: dying as a process of well over an hour of exhausting singing - no wonder that the first Tristan, Ludwig Schnorr von Carolsfeld, actually died of exhaustion after the first performances in Munich in 1865. Following his demise his widow Malvina Garrigues could not bring herself to continue with her career and she retired from the stage.
This Tristan is turning into something terrible! This final act!... I fear the opera will be banned - unless the whole thing is parodied in a bad performance: only mediocre performances can save me! Perfectly good ones will be bound to drive people mad, - I cannot imagine it otherwise. This is how far I have gone!!" (Wagner in a letter to Mathilde Wesendonck)