Strangely, I feel like whatever that Ririha tries to do, it won't have any effect, as in, Mimika wouldn't have any problems solving the situation (probably not entirely). Yeah, I know (or "I guess") that's a little hard to see happening, but I really feel that way... but well, we shall wait and see...
PS: I read some of the comments (obviously not all of them, because, holy hell, that's a lot), and honestly it was a bit strange to me seeing so many people thinking Suzumori would turn Yandere... I myself didn't think that, not even for a second (or am I the strange one here?).