Age gap, post apocalyptic society

I just read this short story on ao3, called Saved by Chrisowl, and I want a book like that. I want the mmc to be older, grumpy, possessive, and the fmc to be a bit naive, especially to how he feels. I want her to think he’s annoyed at her, but for her to be too desperate to leave him. I also want him to be attracted to her, but for it to take some time before he realizes that he gets angry at other guys trying to interact with her, bc he’s attracted to her.