I'd normally try empathizing with her here but she arrived to find him depressed and instead of using more positive reinforcement to encourage Nack, she did the exact opposite (And the worst possible type of it to boot). That wasn't her simply getting frustrated, she acted similarly to some of the worst possible dog owners I've seen growing up. (Turds who hit them when they start barking non-stop or break something... strongly...)
I don't give a crap if she, for some reason, can't live without him or anything like that... she deserves to be seperated from him. And from looks of it, it's going to end up that way