My brother I (a man) have been sexually molested before by another girl in class and I felt powerless and disgusted, what do you think he would feel after someone he knew and trusted so much raped him. Dude fuck off you don't know shit
Let's also not forget about the whole society "standards". According to society, there is no way a man can be a victim of domestic violence or even sexual assault from women, because we are men. Even if a guy does report them, they will most likely be laughed at, which has happened plenty of times before. You could even see in the latest chapter(spoilers ahead!! I tried using spoiler tag, but it is not working!!) when the MC's girlfriend began questioning why he didn't just pushed her(the teacher) away, since he was a man.
All in all, you can be a victim of sexual assault, no matter the gender. Especially if you are a child(which the MC was at the time), it can be a very traumatic experience, since a child's coping mechanism is not quite well developed yet, and so confusion and fear is the most common response.