I live in a dorm. We were six people to one kitchen, all of them calm people that doesn't cause much trouble, plus one girl with a strong enough will to keep the rest of us in line. It was the perfect combination.

Then Princess Bitch moved into the seventh room. She doesn't actually want to study, she's just here because her boyfriend lives nearby. She doesn't give a fuck and skips cleaning days, leaves dishes everywhere and then gets mad if you point it out. The bad mood influenced two other people to also stop caring.

To top it off the strong-willed girl is now dropping out because of an illness. How do I prevent this from going completely downhill?