Well, Lilac Time, Blossom Time, and Das Dreimäderlhaus (the show they’re both based upon) all have Schubert suffering unrequited love over various, usually fictional women. I thought Schubert was gay, but Wikipedia claims his friends all had different opinions on who he was attracted to, and of course it’s possible they were all correct and he was bi. According to the link below, the popularity of the original show started a whole trend of operettas based on the fictional unhappy love lives of famous composers.The movies I'm less sure about.
https://web.archive.org/web/20070707075837/http://www.franzschubert.org.uk/articles/mlbhist.html