The One That Got Away (Red Beauty & Red Snow). I read a fic somewhere on tumblr that I believe had the same name that inspired this. Basically the story to this vid is in FTL Snow chooses Charming over Red and breaks her heart. After the curse breaks In Storybrooke Ruby is still sore over it until she meets Belle and she begins falling for her. Snow, seeing how Ruby is slipping away from her, decides to let Ruby go in order for her to be happy with Belle even though it hurts her to do so.
Features The One That Got Away (Trailer Version) by Katy Perry
I own nothing in this video
EDIT: I finally found the fic that inspired this:
I absolutely love it :3
Tags: The One That Got Away (Red Beauty & Red Snow), Once Upon a Time, OUaT, Snow White, Mary Margaret Blanchard, Prince Charming, David Nolan, Ruby Lucas, Red Riding Hood, Belle French, Red Snow, Red Beauty, The One That Got Away, Katy Perry, Snow, Mary Margaret, Ruby, Belle, Ruby x Belle, Red x Snow, Ruby x Snow