Ralph made several mistakes in the novel, leading to his alienation from the other boys. First, he underestimated Jack and the power of mob mentality. Essentially, Ralph didn't know how to deal with Jack. He tried to force the hunters to his will, but Jack convinced them to form their own group. Once the meat was offered, the other boys couldn't resist. Ralph's logical desire to keep the fire going seems unreal to the boys, unlike the meat which they can smell and taste. He also fails to rally the boys in any way. Unlike Jack, he has no concrete results to show. The fire goes out, he can't fight the terror of the "beastie", his shelters collapse, the boys lose all sense of hygiene, etc. Jack, on the other hand, offers a real alternative; in his group, you can do whatever you want, and eat as much meat as you want. You just have to be willing to obey Jack. The other boys are willing to do this, and it almost seems as though they've been waiting for someone to step in and take control. Ralph tried to be democratic in his leadership, but Jack's empirical rule works much better on the island.