Shiori's relationship with Ruka is really messed up. Seriously. Ruka bates her with a lie, and she responds with another lie. Shiori seems very pleased with herself when she's with Ruka. After all, doesn't being with a popular guy make her better than Juri? Then, of course, there is their happy little ride in the Akio Car, and Ruka's duel with Utena. Ruka doesn't seem to care if he wins, and blames his failure on his Rose Bride, which ends up catching Shiori in her lie. Following this is their very public break-up, in which Shiori screams and pleads like a child. She then repeatedly leaves messages on the man's answering machine.

IMO, Shiori acts childish through the whole Ruka incident, even for her. The end result is basically that she sinks even deeper into her inferiority complex.