Everyone seems to have forgotten that Ouji-kun still doesn't understand what is going on, just the Himeno-chan can get angry about weird things and doesn't want to trigger that. Plus he doesn't understand his own confusing feelings yet.
I actually quite like Rin. It's nice that our boy is actually conscious of Himeno enough to warrant stopping Rin from getting too clingy, but I actually feel kinda bad for her!
Her place has been usurped right from under her nose.