It’s not Shuuichi’s fault nor is it Maki’s (if there are people blaming him for being raped.) The main issue at hand was the lack of proper communication which unfortunately lead to the series of events that happened afterwards. No one is to blame because it’s humane mistake to make, even in romantic relationships so let’s not blindly point fingers.
I'm not saying that everything the seme did was right but you can NOT blame him for Maki getting raped. The only people who should be blamed are the rapists and that's it, don't try to undermine their crimes. Shuu did think of Maki that way but wanted to wait until he was older (which is actually a pretty admirable thing). Even if Maki didn't go to the club it would've happened at some point because those assholes had a grudge and wouldve sought maki out. Shuu already probably blames himself. Blaming someone else besides the rapists is wrong and judgmental.
Everything is fucking shuuichi's fault. If had just been a fucking man about it and told maki he didn't want be with him like that. Or he didn't see him in that way instead of laughing at him the maki maybe have went to that damn club. The only thing shuuichi did fucking right was get the bastards who raped maki other than that shuuichi was an asshole.