In the novel Lord of the Flies by William Golding, does Ralph ever show interest in the welfare of the group? If yes, in which part of the novel?

Yes. Towards the end of Chapter 7, the majority of the boys are on an expedition to hunt pigs and find the beast. The boys continue to climb the mountain after missing an opportunity to kill a pig, and the sun begins to go down. Ralph notices that it is getting late and thinks about Piggy and the littluns on the other side of the island. Ralph imagines how scared Piggy and the littluns are and suggests that the group turn back while the sun is still out. Jack mocks Ralph for worrying about Piggy, but Ralph insists that someone head back through the forest to let Piggy know they will be back after dark. Fortunately, Simon volunteers to travel alone through the forest to bring the news to Piggy. Jack then tries to take the lead and insists the boys continue climbing the mountain. Ralph again thinks about the welfare of the boys by considering that there will not be enough light to traverse the rough terrain up the mountain. Ralph doesn't want any of the boys to hurt themselves climbing the dangerous path up the mountain at night. In both instances, Ralph shows interest in the welfare of the group of boys.