What is the main conflict in Dancing at the Rascal Fair by Ivan Doig?

Lucas's live-in mate, Nancy, is part Indian, and Rob is soon smitten with her. Angus, fearing a family fight in the making, plans to leave, but Lucas offers to help the two get homesteads started, including the purchase of sheep, and Angus and Rob move immediately onto the land near Gros Ventre.