I pulled this out of my list and it's a while ago so I forgot but here
https://www.mangago.me/read-manga/hana_no_miyako_de/
This one's popular so you might have already read it but ts hurt a lot I can never forget it even if I read it a long time ago
https://www.mangago.me/read-manga/hate_no_kouya_de_vacances_wo/

Like ykno they divorce or just break up and stay friends or well, even if it's like one of the partner dies.