My Best Friend Is the Female Lead in a Post-Apocalyptic Space Novel

My best friend is the female protagonist of a post-apocalyptic space-themed novel. When the apocalypse struck, she appeared at the entrance of my family's small supermarket, begging me to take her in. I kindly took her in, but she used her spatial ability to steal all the goods from the shelves and ran away. I was left alone, pushed into a horde of zombies by my enraged brother, and my body was never recovered. My death was so gruesome that my resentment remained, and I became her spirit. Seeing with my own eyes her entire spatial dimension filled with supplies, I realized she had already taken the entire warehouse of the city's largest supermarket, yet she was still insatiable, never considering leaving me a way to survive. It was simply because she thought...