After the trip to the beach, Gene flunks a test because he spent his study time at the beach instead of in his room. When he and Finny talk about how much Gene studies, Gene begins to suspect that Finny is trying to keep him from studying in order to make sure that Gene doesn't overshadow Finny academically. Gene wants to be valedictorian so he can prove he is just as good as Finny is at something, so he believes Finny is trying to sabotage his studies with trips to the beach, club meetings, blitzball, etc. His own jealousy of Finny leads him to this conclusion, even though Finny never directly says anything to prove Gene's theory. This all adds to Gene's guilt later in the story when he figures out that Finny was just trying to be a good friend all along.