There were two doujins I used to read a few years back on g.e/fakku/hentaischool (not really sure exactly where) which, for the love of me, I can't recall now.
The first one has multiple chapters and focuses on a student council president (short-haired) and her boyfriend. Pretty much vanilla at the start until it gets kinky (sex toys, anal, and whatnot) as the chapter progresses. Chapter 4 of it, if I recall correctly, becomes a rape scene where the student council pres is gangbanged by her boyfriend and bf's friends. Never really got to finish reading it since that chapter wasn't translated.
The second one is an incest story where the two siblings were having sex on the couch. They forgot to clean it up and their mom saw it and thought that their friends are coming over and having sex at their place. Scolded the two of them. However, the second time the siblings had sex, they were caught by their mother and were furious at them. This led to their mother leaving them.
Memory is pretty hazy, but this is as much as I can remember about these two materials. Hope you guys can help me out.