Phantom of the Opera (Rigoletto) 

Fans of this movie will either love me or hate me for this. Regardless I'm sure most people who've seen the movie has thought this at some point. I'm not implying that the relationship between Ribaldi and Bonnie is sexual or romantic, I'm well aware it's not. Basically I'm just comparing the basic plot lines of both stories (deformed guy teaches girl to sing). And honestly, the song itself isn't all that sexual or romantic to begin with, and after listening to the song itself it really does fit their relationship. If you haven't seen this movie before, I definitely recommend it, especially if you're a Phantom fan. It truly is a beautiful movie and definitely underrated.