What is the song superman by taylor swift about?

im kinda confused on what shes trying to get across. i get part of it but i want the whole meaning.What is the song superman by taylor swift about?It's about John Mayer. She says "I loved you from the very first day" Which is the secret message on "Dear John."What is the song superman by taylor swift about?every taylor swift song has to do with some kind of lost romance when she was 15 years old, and she'll never get over anything. take a guess