Ok..
Here's some coments then.
1) There's hardly any introduction. You don't know any of the characters very much. It just starts and there's the zombie invasion. Therefore most readers won't really care when the characters die so quickly as they do in this story.
2) Chapter 3 doesn't really make sense. She just randomly kills his girlfriend?
3) Who are the other characters anyways? People he just runs in to? People he knew before?
4) It gets repetitive after a while. Same general theme through the whole thing. First they kill some zombies. Second they meet someone else.
5) What's with the guns they have? He has a pistol laying around when it starts? How does Sabrina have a minigun
6) What are the zombies supposed to be like? First it makes it seem like they're the typical zombies (mindless killing brutes) but then there's this.
It doesn't really fit in.
7) The return of his girlfriend at the end doesn't fit in at all. It states earlier he's dead, and she could never have survived bleeding from a gun wound in the middle of a zombie-infested place.
Please put line breaks at appropriate places. It makes reading these much easier for me. So instead of
I'd format it like this.