Why did mcmurdo and ettie make a plan to leave vermissa valley?

One night Ettie goes to surprise McMurdo. She creeps up behind him, but, to her horror, he reacts fiercely and springs for her throat. He then recognizes her and apologizes, but she is unnerved by the look she saw in his eyes. She cries and begs him to stay away from these violent men. She proposes leaving the Valley of Fear. McMurdo says he cannot do this right now, but finally says that he will work to make it possible for them to get out of the valley within six-to-eight months. Ettie is elated.