This song expresses regret over ending a past relationship and longing to go back and change what happened. The singer wants to apologize for how things ended and wishes they had realized what they had when their partner was theirs. They want to go back to December and make things right by changing their mind and loving their partner properly. The song describes missing their partner's smile and the night they first saw the singer cry. It suggests going back in time to change what happened but acknowledges that can't be done.