This one is about a guy that fell in love with a fit from his class after seeing him being Sexally harassed by others. But the uke doesn't want his help. The seme sits behind him and often looks at him, which annoys himself. I feel like the seme has walked in on a situation a few times.
Is it this one:
http://www.mangago.me/read-manga/majouu_school_days/
When ever I read manga with good sex scenes I get turn on and want to have smut sex with them(▰˘◡˘▰)