I would overall recommend all of tsurukame mayo's works, but she does have 2 works within the same friend group, "Mikami to Sato wa Mada Yamashikunai" and "Akari to Kare wa Nayamashii". I would also recommend, ashita wa docchi da, there are like 3 gay relationships? There's also Janome's works, "Yoi yoi Monologue", "Tasogare Outfocus" and "Zanzou Slow motion" which take place in the same school and you can see mentions of the other relationships within each manga. And also Suzuru Minta's works overall are great and she has 2 mangas "Cupid ni Rakurai" which is then followed by "Kanshaku Dama no Love Song". Also "Seitokai Yakuin Toshite Mondaiji wo Kousei Saseteitara Nazeka Love Come ni Natteita Ken". "Chirijiri Yuku No" has 2 friends who have their own relationships. "Sukiyanen Kedo Dou Yaro ka" Has 2, Mie Hariachatte Surechigai" has 2. Lastly, not my favourite, but Sakura Nico has like a bunch of works that are all set within the same school. Sorry if this is a lot lol
please reccomend me more mangas or manhwas like this where the whole group is gay and have their own stories