God I would love it if it turned out they'd had a massive barney and couldn't bear to be in the same room together but it seems unlikely: Gio is, although a dick, a pro at work, and seems to be able generally (pace Richie) to get on with the job. They were rehearsing till Friday just fine. She did post yesterday about the actress Haydn Gywnne dying, who she seemed to know. That and the deleted post about MH suggest maybe that she'd been struggling for a bit and then imploded.
Or maybe Gio vehemently attacked JK Rowling and she'd had enough..