We may never know who she's singing about on the ballad, which will appear on her October 25 release Speak Now. But she told MTV News that the time was right for her to write a song in which she said sorry.
"Well, I've always sort of written songs about situations in life, things that needed to be said," she said. "I write songs about people who deserve to have songs written about them, and whatever they need to hear, whatever is the right thing to say to that person, ends up being said."
On the tune's chorus, Swift sings, "So this is me swallowing my pride/ Standing in front of you saying 'I'm sorry' for that night/ And I go back to December all the time/ It turns out freedom ain't nothing/ Missing you, wishing I'd realized what I had when you were mine/ I'd go back to December, turn around and make it all right/ I go back to December all the time."
She says now that those feelings stemmed from a relationship during which she was "careless."
"I've never felt the need to apologize in a song before. But in the last two years I've experienced a lot, [including] a lot of different kinds of learning lessons," she said. "And sometimes you learn a lesson too late and at that point you need to apologize because you were careless."
This is the fourth song released in advance of Speak Now's late-October release. The release of the album's first official single, "Mine," was followed by the debut of "Innocent" at the VMAs in September. The album's title track debuted on October 5.
Who do you think Taylor Swift is apologizing to? Let us know in the comments!