I will base my following comments as if I were the Mc in a real life scenario:
1. First of all, just like anybody else I would avoid anything that would land me on jail. The idea of committing a *crime* and getting my ass fucked in prison scares me to death, so I would NOT fuck the girls *yet*
2. I would not reject any of the girls, instead I would, like the one girl suggested tell them to ask me again after they graduate. Why? CUZ I don't wanna get my ass fucked. And they are considered adults after high school.
3. Now let's say for the unfathomable scenario that the girl or girls sexually attack me outside school. They literally jump me and start undressing me and doing all the sexy shit. I would probably most likely fuck em. I know I would be contradicting 1 & 2 but at this point how the fuck do you even stop it? You would have to be the biggest fucking beta to reject the sexual advances of 3 grown fuckibg girls. If someone blackmails me outside the girls I would have them make video & written statements that they seduced me and it wasn't the other way around.
If they did wait for graduation or attack me I would try to discuss a poly relationship with them saying how it would make everyone happy happy. Doesn't hurt to try you know I seen married couples in poly relationships so in this day and age something to consider.