Host of a ghost

What am I? What have I been doing? I see myself through her eyes, I think I see love I think I see my reflection. But then again I look behind her and I see someone else, suddenly she turns her back on me. I thought she loved me, I thought I meant something. I'm nothing in her world, she said things to me but in the end nothing stood. I look and there's someone else there, it's like I've never existed. I was just a ghost, no, not even that. I was the host of a ghost...