The main question of the story is: Was Daniel right or crazy? Because if the former, then the story becomes completely unrealistic, but it's not clear where the "real" Liz came from. But I'm more inclined to the second version: Daniel has lost his mind. Because of his paranoia about Liz, he becomes emotionally abusive to her, refusing to eat her food or even talk to her, and if Liz told the truth about her injuries, physically abusing the girl.
Liz, in turn, becomes a martyr to love and stubbornly refuses to believe that Daniel is doing anything wrong to her, falling into the most abusive relationship possible. At the end of "R.M.F. is Flying", Liz dies after cutting out her liver because Daniel told her to, or, more likely, her liver is cut out of her by him.