a) You can pretty easily tell people are/have been physically intimate with each other, expecially when you interact with them every day in close proximity.
b) What would she even tell them to get them to go along with something like that? "Yeah so Haru went after me and I rejected him, can you all act like we had sex together so we can break his spirit?". Doesn't seem plausible.
Then again, her fucking EVERYONE in the club is equally implausible, imo, even if they were all inexperienced virgins after she dumped one or two of them the others would probably have wised up. Unless we're meant to understand that she was fucking them all at the same time, which is even more unlikely (considering she was also supposed to be inexperienced at the beginning).
