So, everyone including the female teachers are lesbians at this school?
Hibiki has dated boys, so she's either bi or het.
So has Mariri, evidently (since we're not shown her ex, but know he existed because of that one chapter with Mayuyy asking about kissing).
I think the rule in this manga is probably generally that they CAN find guys attractive but will inevitably fall in love with a girl in the end.