TBH, I don't think she's even realized Reid's gone... She's been kind of avoiding contact with him and hasn't even tried talking to him after she's run off to Joonhae so she might still be under the belief Reid's in Johto? But I might be stupid and forgot it was mentioned in one of her threads so if I'm wrong, forgive me.

But if she did knew...mixed reaction? She didn't like Reid one bit but he was kinda one of the few things in Johto (save for her Eevees) that kind of remind her of Mio? She might be slightly upset but would be secretly glad he's out of her hair. Emphasis on "secretly" cause even if she hated Reid, she still feels rather horrible about being happy for someone's departure and doesn't want to be seen as a "cold person".