Are we talking theater? Or in general?
Because, if we're talking in general, then i reckon At Last and You Raise Me Up are pretty damn romantic!
But showtune wise? Ohh, there's too many to mention. I like I'll Cover You (Rent). But I'll think of more. I'd Give it All for You (Songs...) also rates for me.
"...But Kungurtseva reels off multiple fouettes and the tape is stopped so she can take a bow. The Jester, an abomination introduced to Swan Lake in Soviet times, extorts applause from the audience. The cuts don't help the storytelling, the production is bare bones and they go for the '50s-style happy ending.
The audience cheers like mad at the end. It's the Russian ballet, after all..."