Lyric discussion by Cantabile 

Cover art for Glass lyrics by Ingrid Michaelson

I love the line "you see through me like I'm not there." It sort of works 2 ways. First he sees through her in the sense that he knows her so well that he understands her, so much so that he sees through her like glass. But then, after they lose whatever it is they had, he sees through her like she isn't there, as if she were invisible, a stranger, who no longer exists. Beautiful song XD