Despite this more or less being her plan, Katina was actually a little surprised that Subaru had had the nerve to yell out like that. Calling for Katina and Akiha to stop, like it's not exactly what Katina wanted to do.

Being shoved like that by the girl - the half-demon - that she'd been kissing was less surprising, and she stumbled back with little difficulty keeping her footing. As cute as it would've been to see her embarrassed, this was what she was going for.

...hopefully they don't kill each other. "Hey, hey now. You two ladies don't need to get all aggressive with each other."