This guest clause is irrelevant . She is not a guest at all . She is a tenant or occupant and that is prohibited by your lease . Your options are have her move out or sign a new lease with two occupants . When the hotline said having a new agreement with both of you was illegal I am sure what they meant and probably what they actually said was that the landlord could not require you to sign a new lease at a higher rate . That is true . However your landlord is also not required to allow you to move her in at all or to enter into a separate agreement with her . So if the option he is giving you is to sign a new lease with double occupancy at a higher rate or not have the GF move in then you have those two options and you can chose what to do . At this point your landlord can also evict you for having double occupancy when your lease specifically prohibits that . He can also revoke the offer he made to allow her to move in with the new lease .