Hello!
Hinamix by Ryoh-zoh is my favorite doujin of all time. link: https://nhentai.net/g/429880/ It's known as 429880 apparently. I highly recommend it.
It's really funny, but something more serious would also be kinda appreciated. Anyways, as the title suggests I really want some more doujins like this to read/analyze during the summer. There really isn't anything like this, and this doujin needs to be more popular/appreciated as it makes ntr kinda wholesome. Me and my partner really like this stuff too, so you'd be helping 2 people lol.
If you haven't read it (probably), a good summary would be that in the student council (they're all student council members), the main girl Hina is a slut and get in a relationship with a innocent guy who likes to watch her get fucked and occasionally fucks other girls as well, but basically remains loyal to her. Hina's bf doesn't get hard unless he's seeing Hina, which is why he doesn't care if Hina fucks other people unless he's not there to witness it.
Spicy details: If you want details, I just like how the mmc is an adorable sleazebag and lets his gf get fucked/fuck for his pleasure. And the gf is really slutty, and kinda lets anybody take her. And there was this one chapter where she watches her 'rival' do her boyfriend, which is my fav chapter.