The ending is absolutely the funniest outcome.
So, in addition to this, I have read the h-doujins. The ending there is a bit more bleak, but compared to that, this has much stronger character work since it's mostly a drama instead of porn.
Iida is much better here as a character, and also is pretty layered. You get more insight into who she is, what she's about, and why she'd behave the way she does. The sex scenes with Fujino, while it's probably true she likes it, she was clearly just dissociating in one of the chapters, using it as an escape from the expectations of her mom.
It also kind of shows that the escalating wet-blanketness of both her and Kousei is the main conflict and it's quickly resolved once one of them stops being that way to get the other one to be that way. The whole Manga couldve been over if at the festival Kousei just stood his ground and said something else to Iida instead of letting her walk off with Fujino and friend (especially since it turns out that is not when they go have sex, even though he thinks it is)
The ending of her lying but clearly being affected and gratified by seeing his expressions to hearing or thinking about her having sex is really funny, but also shows that... She's truly committed to him because it's her 'special person.' She has probably kind of liked him for a while. If he had just been as forward and confident as Takashi or Fujino even only once then they could've hit it off after maybe the first time (like imagine he doesn't just dip out at the 2nd day with Jenga or whatever).
Akaneya is a great addition, even if her being assaulted is grossly bizarre, since Iida is assaulted but never raped in the two attempts at that. It's meant to be another ntr zinger, but it feels out of focus with that arc. The final extra chapter showing her mind of open up to her coworker as an adult, and going back to her high energy self when she sees the attractive features in her coworker the way she saw them in Kousei is a good send off for her. I wish Niiyama had her doujinshi ending though, with her Kouhai (I'll assume it happened).
It's easy to imagine Kousei and Riho getting together in the future, since they're compatible in a really funky way, and she's unlocked how to make him horny. And that's a better ending than the 'class reunion' doujin (which feels alt-universe anyways, since it doesn't cohere with the ending of the doujin).
Realistically, it was just fine, like the doujin is like 4/10 while this is 6 or 7/10 but I know some people would hate this passionately and some people would like this more than me, so reading it for fun is good
