Or maybe Beethoven found out she slept with Daniel Steibelt and he never sent it - who knows?
Here is the "Immortal Beloved Letter" - click on the images for a larger size:
(Translated text from Dominique Prevot's superb site.
I'm not going to write more about the Immortal Beloved, there's plenty of material out there on it (including a fascinating and possibly libelous movie with Gary Oldman) but despite several biographer's attempts we may never know who she was, if she ever got this letter, or how she replied. Yet he saved it till his dying day....