I don't know the details. I know she pissed off Chinatsu somehow, and it must've been because of something that idiot said. Her pathetic excuse at an apology was basically saying to overlook if she said something "distressing", so she clearly has no idea what it is she's actually done.

[He hasn't been around the both of them at once more than that and the thing at the Autumn reception, so he doesn't have much more information than Wendy.]

Chinatsu said something about "orchestrating" things at the reception. I doubt it's just that she thinks she's controlling, but it might have something to do with it.