Well we know that Beethoven was notriously grumpy. He was also the greatest musical genius to ever live. That of course is a value judgment,and if you disagree with it you are a terrorist.
So the real question is not how well he wrote for the human voice(quite), or if he was a manic-depressive(no), or why he and Haydn didn't get along(who gives a shit?) but how much did he get laid? I say a lot and here's why:
Fur Elise, or the Bagatelle in A Minor, is designated as WoO 59. For those who haven't read my Seductor's Guide to Classical Music(trademark pending), which is everyone because I haven't written it yet, WoO means 'without opus.' I have been informed that it is from the German werke ohne opus which translates to "work without opus [number]."
The title 'Fur Elise' in German is just a dedication meaning simply, 'For Elise.'
Now the piece was published in 1810 when Beethoven was 40. His first piano sonatas were published in 1783 when he was 13, so we can safely say he was capable of writing a comparatively simple piece like Fur Elise 27 years before he supposedly actually did.
Now, this will seem like pure conjecture now, but I am confident that when scholars get around to reading some of those old diaries that everyone seems to have kept in the 18th century so some humanities major can get their Ph.D. they will discover that Beethoven had that piece for many years before its now officially recognized publication date.
Why did he never make it public?
Because he used it to score more pussy than a bonobo.
First look at the properties of the piece: it can be played by one person. Someone of Beethoven's piano skill would be able to play it and still hold a conversation. It demads no attention, or concentration. So a woman goes into the room to meet the great Beethoven and he's sitting in there alone and he's playing this tune. I imagine the typical conversation went along these lines:
Julie: "Hello, Mr. Beethoven, what's that?"
Beethoven: "Oh, just a little piece I'm working on. And please, call me Ludwig."
Julie(nervously): "It's beautiful. What's is it called?"
Beethoven: "I was thinking of calling it 'Fur Julie'"
Julie(blushing madly): "Oh Beethoven,really....?"
Beethoven: "Absolutely. Here let me show you the first notes. Come sit next to me..."
All the various lures he is holding out here are breathtaking. Beethoven is offering everything anyone could want: immortality, their name attached to something beautiful, the chance to meet whatever noble Beethoven was working for at the time, and of course, making a nice guy out of a notorious bad-boy.
Now is anyone going to tell me that that would not have gotten him laid? And he lived at a time when social conventions were such that all the ladies in town couldn't publish in the local scandal sheet how they were tricked and seduced by Beethoven.
Historical evidence will eventually prove that there was a girl named Elise that was proving very hard to fuck, so Beethoven finally had to play the piece in public. It was probably at this point that he got that scowl that we see him with in almost every representation of the man. He was giving up his best seduction method and deaf. One or the other would be bad enough, but the combination of both probably kept him pissed until the day he died.