you can't really call it bullying when she basically provoked such a reaction from them. Charlotte said that she feared that Cassi would end up staying in with her fiance instead of persuing a most likely successful modelling career. and Cassi ended up doing exactly THAT.
Demelza was told off because she bullied someone, that means she attacked Alamela without provocation.
when you invest a lot of hope and trust into someone because you do know things better, wouldn't you be angry when that person would simply tell you to "toss off" and show that she doesn't give a damn about the trust you put into her? what Alex and Charlotte did was basically venting. NOT bullying.