After Gene jounced Phineas out of the tree, which resulted in a really bad breaking of his leg, Gene felt empowered and fearless. At the exact moment after Phineas hits the ground, Gene runs and jumps into the river and "every trace of my fear of this [was] forgotten" (60). He forgot his fear of heights, of jumping into the river, and of being less than Finny. Gene even gets bold enough to try on his friends clothes in chapter five while Phineas is in the infirmary. But eventually, as with every indiscretion, when Finny was able to receive visitors, Gene had to face the one whom he'd harmed.
When the doctor tells Gene that Phineas won't be able to play sports again, that is when Gene breaks down and actually cries. The next question in the reader's mind is whether or not Gene will apologize and admit his mistake. The problem is that no one blamed Gene, not even Finny, so it was easy for Gene just to avoid the topic all together. Just as Gene is about to confess, though, the doctor comes in and interrupts. The consequence of these action on the boys' friendship could have been devastating, but Finny forgave his aggressor and that made things worse for Gene. From that point on, Gene questioned his own character, felt guilty, and couldn't really talk to his best friend. He avoided too much contact with Finny, but he also became more loyal and a better friend in the end.