Lyric discussion by McHaggis 

"Civilian" suggests a non-combatant, an unarmed person caught in the crossfire. In this case, it could refer to the singer's lover (ex-?), who walked into her emotional crossfire, so to speak. I think this works better than the other connotation of "civilian" (that is, an outsider to some group). The rest of the song dwells on the singer's emotional complexity, insecurities, and regrets, suggesting that her lover entered into the relationship unprepared for her intensity.

Oh, so she's basically singing about my life.

i think youve got it. hes a civilian in her crossfire..

An error occured.