Sara has been treated SO badly by the other HMs, its actually really upsetting since she hasn't done anything wrong, just upset bully Darnell. The only friend she has in there is Lisa.
Also it's very clear from this that Kat/Darnell/Mo/Rex/Rachel have some sort of BB US type of alliance which is so annoying because thanks to them being selfish we've had to evict good HMs.