Or maybe Kurohime is horny enough to get past any hangups, and Rin would be okay sharing Toudou if she was the one in control of who and when . . .
After the Dodgeball game ended as it did and with how both Rin and Kurohime seem to appreciate each other by the end of it, i believe Kurohime can come up with an arrangement for Rin to monopolize her between the two of them. It doesn't seem like they would actually clash that badly if they can join together to make it so Toudou can't go skirt chase, either accidentally or purposefully.
In other news, mulling over it a bit more, Mukai's infatuation seem a bit more "suspension bridge"-y than nurtured affection right now, so I guess we'll need to see as the story progresses what's it actually supposed to be (specially with how, after Toudou was shoved into the ground by Ookado, Kamisada hasn't talked to her about the whole "make me your girlfriend" thing, yet seems to remain with some affection of dubious nature for Toudou up to the Dodgeball match -let alone the way that Ookado's affection for Toudou ended up more as her sexual awakening but without any desire for Toudou herself).