Lyric discussion by Marinalise 

Cover art for My God lyrics by Bombay Bicycle Club

I think that this song is about finding out that your significant other has cheated on you. It's basically describing the argument he's having with his partner, and how angry and heated it gets. Lines like "paying no attention to the thoughts of your dear friend" and "sound of my power" lead me to to believe this. The title itself "My God" and the way he sings it in the song shows the frustration and utter disbelief he's in about the situation.