I got it
The reason Edward didn't show up is because Susan killed that good man, he doesn't exist anymore. After being dumped brutally, he continued to struggle in his writing for a while until he decided to sell out and write a book about that is a murder/rape thriller, blood, sex and violence sells. In his letter to Susan, he mentioned that this book is completely different from what she read from, proving that he completely changed. AT the the end of the story, the cop tells Edward he's a good man, shortly after he kills the murderer and himself. The good guy is dead.
I think the director doesn't want you to think that Edward killed himself too in reality because at the begining of the movie, you can see him park his car at Susan's villa to drop the book himself in her mailbox.