With the way Chita treats Seto with hostility, I'm worried the author is going to have her be another "psycho lesbian" (look it up on TV tropes) that's obsessive over the female lead. Everyone loves seeing that kind of character appear in rom-com manga.
I'm hoping that Chita's just being a good friend, making sure Seto is not taking advantage of Anjou.
I just hate the obsessive friend that actively sabotages any progress with the main couple, regardless of gender. Unless the character actually has a chance with one of the leads, then there's nothing to be gained from the friend getting in between the main couple and the author is just wasting everyone's time.