What is the main conflict in A River Runs Through It by Norman Maclean?

In A River Runs Through It, Norman is approaching middle age and still finds fly fishing to be an enjoyable pastime with his brother, Paul. Norman and Paul spend a great deal of time fishing together even though their lives run in different directions. Norman admires Paul's expertise at fly fishing and finds himself often overshadowed by his brother's skills. Paul does not try to criticize Norman's shortcomings as a fisherman, however, which makes it difficult for Norman to discuss with Paul his behavior outside of the world of fishing. Norman knows his brother needs help as his drinking is beginning to interfere with the rest of his life, but Norman cannot speak to Paul about it because he feels that he does not know his brother well enough to criticize. When Paul dies because of a fight, Norman feels as though he let his brother down.