The fire goes out because Jack and his hunters were not tending to the fire. They leave to hunt and the fire goes out. In the meantime, Ralph and Piggy go check on the fire:
They reach the fire, which had gone out. The choir members who tend it are nowhere in sight. “A pile of unused fuel lay ready.” Ralph is livid. They see below the choir members emerge from the forest waving sticks and chanting. Jack is leading them. They are carrying the gutted carcass of a pig on a stick between them and chanting “Kill the pig. Cut her throat. Spill her blood.”
Jack and his hunters did not see the importance of keeping the fire going. It seemed that they were contented without the chance for a rescue that the fire provided. They definitely did not desire to be rescued as much as Ralph did.
Ralph knew he could not keep the fire going by himself. He needed everyone's help. Ralph was afraid that they would die on the island if a fire was not burning to signal for help from ships passing by. Ralph was so angry with Jack and his hunters for allowing the fire to go out.
Jack seemed to not understand the seriousness of keeping the fire going. He was caught up in his acts of savagery. He was into the thrill of the hunt. He enjoyed the power he felt when hunting:
Truly, Ralph and Jack have differing perspectives on what is most important. Ralph is concerned with being rescued. Jack is concerned with gaining power and control over his hunters. Jack is domineering. He desires to be the chief. Ralph is about what is best for everyone on the island:
Jack does not understand Ralph’s distress or the significance of the fire being out...
While the fire is out, a ship passes by. Ralph is in torment thinking that their chance for rescue just passed them by:
Ralph tells Jack about the ship, but Jack appears unconcerned, defending his actions in terms of satisfying the others’ need for meat. 'The two boys faced each other. There was the brilliant world of hunting, tactics, fierce exhilaration, skill; and there was the world of longing and baffled common-sense.'