So this song is about Liam Hemsworth and she thought they shouldn't have gotten engaged so young. Maybe she thought if they had gotten engaged later, they would have been a great couple. Maybe she thought if he knew the song was about him, he'd want to get back together because they broke up in September. She was heart broken, so she did what Taylor Swift does best: wrote a song about him. He just got Swifted by Miley!!!