How does Golding portray the worsening relationship of Jack and Ralph?

Although Ralph and Jack begin the story as friends, their relationship steadily declines as Jack descends into savagery and Ralph clings more fiercely to order and morality, supporting Golding's theme that people must guard themselves to avoid falling into depravity. In the first chapter, Ralph and Jack meet each other, and Ralph chooses Jack to accompany him on an exploration of the island. They get along well with each other despite Jack's jealousy over not having been chosen as chief. In the second chapter, Jack voices his agreement with Ralph about following rules and doing "the right things." But in chapter 3, Ralph becomes disappointed with Jack's not helping with the shelters and being too focused on hunting without having provided any meat yet, and they have an argument. Their two different worldviews begin to be apparent as "they walked along, two continents of experience and feeling, unable to communicate." This shows them beginning to diverge in their priorities, which leads to conflict.

When Jack lets the signal fire go out in order to kill his first pig, Ralph is furious with him. Jack responds in anger, punching Piggy and breaking his glasses, after which Ralph turns to Piggy, not quite realizing how "a link between him and Jack had been snapped and fastened elsewhere." Thereafter Jack and Ralph are more and more at odds. Jack disobeys rules at the meetings and even tries to vote Ralph out of being chief. Jack starts to use face paint and deceives Ralph to get fire to have his own feast on the beach. Piggy and Ralph discuss how things are deteriorating and attribute it to Jack, around whose name "a taboo was evolving."

After the feast on the beach where Jack has deliberately tried to draw boys away from Ralph, Jack develops his own tribe, and the two factions are opposed to each other. Jack sends boys at night to beat up Ralph's group and steal Piggy's glasses, and Jack moves his tribe to Castle Rock. Now Ralph feels completely alienated from Jack. Jack now treats Ralph as an enemy, and when Ralph comes to Castle Rock to get Piggy's glasses, Jack opposes him, captures Samneric, and wounds Ralph with his spear in a fight. After Piggy's death, Ralph is alone and learns that Jack plans to hunt him the next day. What was once friendship between the boys now spells Ralph's death sentence: "Then there was that indefinable connection between himself and Jack; who therefore would never let him alone; never." Ralph says to the captured Samneric about Jack, "What have I done? I liked him—and I wanted us to be rescued." Samneric inform Ralph that Jack and the others hate him and are going to hunt him. Golding uses the relationship between Ralph and Jack to illustrate his theme that if people don't consciously work at maintaining morality and order, they will plunge into savagery, and that those two worldviews cannot peacefully coexist.