[Tempest35]

You're right, holding Rei back would have raised questions but Shidou's father, for lack of a better way to describe his position of power, is 'on the school's board of directors'. Any inquiry would have been shot down and smothered - similar to what happens when there's an internal investigation and to keep the situation 'under control', it is swept under the rug.

So basically, her records show that she has been held back a year for a non-medical reason aka failing. The colleges will look at that and say 'pft, whatever' and leave her high and dry. She'll have to work extra hard to overcome this blemish on her life, all because of her father's work. She seemed more upset that her father actually broke down and cried in front of her than her actually being held back. That and the fact that she'd been wronged by a bad person as well also offended her sense of justice (she IS a cop's daughter after all). Circumstances are just that - circumstances. It's not like Shidou tried to explain why he did held her back - it's not like he asked Rei's father for help on getting dirt on his father - he just didn't care how he got the dirt, he'd dig anywhere to get it.

As for Shidou being all miffed about not getting speared, he's got a big ego - he wants to be acknowledged somehow, even if he does something 'bad'. He wanted to 'break' her in front of everyone, pushing her moral dilemma to the breaking point to where she would just stop and cry.