anchor: Her only hope, if she is unhappy with the perpetual houseguest, is to advise the (official) roommate that 1) the threesome is not a comfortable arrangement for her, or 2) the guest is a de facto resident and should share the expenses--to the tune of one-third.
positive: The woman's only hope, if she's unsatisfied with her guest, is to tell them that a threesome is not a comfortable situation.
negative: The woman must keep her mouth closed if she's not happy with the situation.