Fragbet85 said: Well yes, Elizabeth can be dated and apparently "spend a long time" in FeMC's room.
As for Thedore, it's implied in his meetings that his sisters treat him like crap, so he is pretty much in big trouble.
Or it could be that it's like "OMG my lil bro with a GIRL!?! I'll kill that pervert!" (the pervert here being Theo.) Some sisters just won't let their brothers grow up. Plus I think they'd enjoy cockblocking him.
Or maybe you're right and it's jeaslously. Just my two cents...