The Idea Factory - Where It's Safe
The main character wakes up, having been in the town for several years. They're going through a rough patch in their marriage, but they're working through it in couple's therapy. As the characters are introduced to the reader, the main is struggling to remember them as well. She has a crush on her neighbor, who is supposedly her best friend.
It is established early on that their town is up in the mountains, and that the area around it (the valley) is no longer safe, with rampant crime on the rise. While the technology of the town is mid-2020's, they don't use the internet or cell service to contact the outside world. When the main and the friend go for a drive, they get lost and come to the edge of the mountains, seeing the valley for themselves.
The world outside of their little mountain home was destroyed. It's really 2060s, post climate change, and the town is held pristine by a weather control device. There are still survivors out there that are brought in and paired to help repopulate the world as the control device slowly fixes the world. The main is gay, and is a recent arrival, only thinking that they had been there all along. The therapy, both couple and solo, help control their memories.