Why was Gene hiding his emotions from Finny?

Gene's "realization" of Finny's allegedly competitive behavior "broke as coldly and as bleakly as dawn at the beach" (44); the simile repeats the imagery at the beginning of the chapter, suggesting daybreak as a motif and metaphor suitable to describe many aspects of the story. Gene's language and tone become increasingly more dramatic, perhaps even melodramatic, as he describes the influence that this false realization had on him at the time. He says he was "despairingly in search of something" to cling to, blowing his mental separation from Finny up into something life-shattering, in a way (45). Yet, these words definitely seem added in retrospect; Gene says he does not act differently than normal in the face of this dramatic "deadly rivalry," gets on well with Finny, and devoted himself to his studies (46). Gene's social life remains much the same, as does his outward manner; he does not act as destroyed as he claims to be, but rather he is very much intact, but vengeful. Gene finds the "truth" that he alluded to at the end of Chapter 3, but it is not a truth at all‹it is a dangerous falsehood‹and in this confusion, he also misrepresents his destructive anger as genuine despair.