This song made me cry the first time I saw the movie. It's not as sad as some of the other songs in the movie, I cried because the character who was evil and thought she'd never love again found people to love again.. I found it very relatable.
I didn't cry the first time I watched this movie, but one day while I was listening to this song on loop, about 40 minutes in, something about the way the disembodied voice of Elsa's mother says "You are the one you've been waiting for" really got to me and suddenly it clicked that the whole point of this song was Elsa finding herself and somehow THAT made me cry in the middle of my university's library.
And finally, this song combined with its music video makes me cry because there's something so powerful about seeing a whole life play out. I think what makes me sad is knowing I'll never get to experience it this way.