Analysis of Left Behind

I'd never felt this way until I had to say goodbye.
A feeling of loss so intense, It's like I might actually die.
I can't eat, can't sleep, your face is all I see.
My chest feels so tight that sometimes I can't even breathe.
For it's not like you just moved from one town to the next.
Where you've gone I cannot follow unless I take drastic steps.
Carrying on, as usual, feels like I am saying I don't care
But I don't know what else to do.
...My God this isn't fair.
I'm told need to get through this, that things get better with time.
But it's the worst feeling I've ever known
                           To be the one who's
                                LEFT BEHIND.