So, Shinohara asked Ayaka about the location of the café and then showed up there, so clearly she went there with some purpose in mind. Since Shinohara is involved with both the MC and the boyfriend, it seems overwhelmingly likely that she was there to see one, or both, of them. But the boyfriend was surprised to see her there, so clearly he didn't tell her he was going (and why would he, since it was a mixer). And Ayaka mentioned she was confused as to how Shinohara knew that Ayaka and the MC knew each other. Even if she knew Ayaka since before, she just met the MC. So how exactly did Shinohara find out that either the MC or the boyfriend (or both) would go to that mixer? She could have been stalking one of them, or asking around about them, or perhaps she knew the MC from before somehow, which would explain how she could know that the MC and Ayaka are close friends. If it's the latter, that raises a lot of questions about whether it was a coincidence that they ran into each other before when she was handing out flyers, and why she never showed up to that café he was waiting for her at so they could go apologize to her boss. Maybe she never had a part-time job in the first place, which is why she wouldn't want him to come along and see her imaginary boss. And if it's the case that Shinohara is strategically approaching the MC, is it also a coincidence that she showed up so soon after he was cheated on by his ex, and that she just happened to have experienced the same thing at almost the same time?