Early in the novel Ralph is identified and elected leader as he
has a "directness" in his manner that the narrator calls a sign of "genuine leadership."
Ralph is the primary representative of order, civilization and productive leadership and wastes no time in trying to maximize their chances of being rescued and organizing shelter.
By chapter 3 Ralph is still concerned with shelter but is now frustrated because he is not achieving what he set out to and he is annoyed at the lack of commitment from the others, especially Jack who just wants to hunt.
That a problem exists at all is only perceived by Ralph. He clearly sees the lack of organization as detrimental. It is only against the backdrop of his perception that the deterioration can be seen at all. Through Jack’s eyes, there is no problem beyond his inability to get meat.
Ralph has a huge responsibility on his shoulders by this point and bickers with Jack. The island is no longer such an ideal place away from the grown ups.
Jack is becoming more influential and Ralph less so as Ralph becomes more afraid of the outcomes and consequences of decisions he may make.
Ralph's fear and overbearing feelings of responsibility affect him seriously and he is concerned that
since the small boy’s death in the fire, the tone of their existence has changed somberly for him. No longer can his actions be performed lightly, lest they rage out of control again.
It is this fear, perhaps, that renders him ineffectual, at the same time making him frustrated by his ineffectiveness.
Ralph has realised that it is hard work and expecting others to follow your lead simply because things need to get done is unrealistic.
Refer to the eNotes study guide and analyses to get an understanding of how the Ralph and the other characters change during the course of their stay on the island.