I'm Not The Only One Lyrics

Lyric discussion by seeing 

Cover art for I'm Not The Only One lyrics by Sam Smith

His ex-girlfriend discovered that he is gay (he revealed this in May of 2014 to the public) and maybe cheated on him because he kept that secret from her ("You say I'm crazy"). Back in the 1960s and earlier, gay people were considered crazy, and she must have been a conservative type.

My Interpretation