how can someone still alive already haunt you?

A Poem by laine

maybe I am beautiful and maybe there are galaxies inside of me but all that is nothing compared to your eyes on a cold day
and maybe just a memory is enough to keep me up at night? and maybe the way you move is enough to make me feel uncomfortable?
maybe I am strong and maybe my soul has a suit of armor but what if I still can't sleep at night
what if I will never sleep at night
what if you were my only hope at a good night's sleep
maybe I had a warm meal and maybe I had three but what if my stomach will always be empty in the space you used to occupy

why am I writing about you as if you've already gone?

how can someone still alive already haunt you?