Well it feels like it's gonna suck for Ishigami. The dude can't catch a good one, even when he wins, at the same time loses. It's a stretch, but I think she's just trying to show him appreciation on a way that defines her. First she sort of screw up trying to have sex with him instead of clearing thins out, but then found out about everything that he went through and started this whole thing for him to have happy memories of school. I know I'm probably wrong, but that's how I see it.
On a personal note, I like couples that have different personalities, because they balance each other, but I think author didn't add too much on them, she always felt like a side girl to me.