Good apocalypse world building or just world building without harem. Preferably bl but will read stallion
These threads is similar to what you are looking for https://forum.novelupdates.com/threads/bl-zombie-apocalyptic-novels.116974/ https://forum.novelupdates.com/threads/apocalypse-bl.119660/ https://forum.novelupdates.com/threads/bl-apocalypse.122375/
Amazing world building, characters and love story. It's by Priest, the same author as Tian Ya Ke and Guardian, both of which had live action adaptations.