Extra person moved in house... I moved out

Though my lease does not specifically state it, I moved into a three bedroom house with the undrestanding that there would be three people living there. The landlord moved a fourth person in (her boyfriend) and I subsquently moved out before the end of my lease. Am I responsible for the remaining months or do her actions reasonably allow me out of the lease?

You normally are still responsible unless you agreed that that was why you are leaving.

...Or if you asserted that they broke the lease and you had to leave etc.