I am sure that many people have lived the story being shown in the lyrics of this song. Some have experienced the singer's perspective, while others have had to experience the other person's perspective. The singer is basically saying that his lover had a 'Pretty Heart". The story in this song is about a guy, who is the singer himself, and a girl. The guy is not that great of a person overall, but the girl is very pure and innocent. She has not gotten a mean bone in her body, and she manages to see the good in everything. But the guy's behavior has become so bad that it has even managed to break the heart of that girl.