Lyric discussion by gofuckyourself 

Cover art for The Spirit of Jazz lyrics by Gaslight Anthem, The

I think this is a retrospective on that relationship you had in high school, where you really thought it would work: thought you'd get married, etc. But it fell apart.

Song Meaning

Agreed. Brian has said his "first wife" (ie Great Expectations, so I'd assume this song too) is someone who he had a relationship with when he was younger. The relationship was, to him (at that point in his life), very much like a marriage. He thought he'd be with her forever.