(Spoiler) Why would he just leave Stormy?

I don't understand what your saying. The other dead girl was telling Odd that there was trouble somewhere else , somewhere else being the key phrase, why put Stormy somewhere else , when somewhere else is where the trouble is.

"Let us die young or let us live forever
We don't have the power but we never say never

I agree. This is a HUGE problem with the script (and the book, i guess...) As soon as he figured out it was the mall, he would be on the phone getting her out of there. She wore that headset 24/7 and was in constant communication with Odd. Yes, he lost his phone at Bobs, but he still could have found a phone. Also when he got to the mall before it all began he could easily have warned her and got her out of there. Just lazy writing. Typical Koontz.

Odd DID know Stormy was already dead, he says so at the end, that he realized it the moment he saw her but he couldn't accept it or it would have destroyed him at the time. So instead Odd did what was right, focus on the lives that could still be saved, which is why Odd is a hero.

And as a reward he was able to spend a few days with and say his final goodbyes (for the time being) to the love of his life.

It's called romanticism dude.

Stormy was DESTINED to die. She was also stupid. He told her to stay home.

I thought that was off, too. He cared so much about her throughout everything and she is his everything, but when he finds out there are shooters in the mall he's there for like thirty minutes and not once goes to her station. Also, I think I remember there was a small opening of time when the shooter was first on the mall floor, to the time he actually shot up the ice cream place. Why would she have not ducked? The ice cream shop was full of people, and when we see inside, there's like no one but stormy. Yet, she's the only one to get shot?

***Spoilers***

Odd gave Viola a speech about destiny. He told her that even if you changed every choice you planned to make because you knew what the future held, you might somehow find yourself in the same situation because that is how fate works.

In the movie, no one has a premonition involving Stormy. Viola and her girls were saved. The group Odd saw initially were saved. Stormy was meant to die then and there.

Odd knew she was dead. In the beginning of the movie, Odd states the dead do not speak. Everyone in the shop was looking behind the counter in sadness just before Stormy rose and at no point from then on did she utter a word. Odd knew she was dead, but could not face letting her go, which he stated as well.

It was covered in the book. By the time he knew it was happening in the mall it was already STARTING to happen, so he didn't want to call Stormy and send her INTO the fire. He states that he might actually be sending her to her death, and that he should trust in their destiny and not intervene otherwise. That by warning her he may change destiny and kill her.
(Of course we learn that this was an ill conceived notion, but that was his line of thought)

I think Stormy didn't act like a girlfriend. Yes, she's very independent, blah, blah, blah. But he begs and pleads for her to stay home. Which she does not and gives some lame speech about not being afraid. If my highly clairvoyant boyfriend had been telling me for days about some huge thing going on and begged me to stay home, I would suck up my little independent self and do it.