what's the significance of the marksmanship differences between Dwight and Rosemary?

Rosemary joins a local rifle club and soon shows herself to be a pretty good shot. She even starts performing well in competitions. Dwight, on the other hand, is still no good with a gun. Like the proverbial bad workman blaming his tools, he blames his lack of shooting prowess on defective weapons. But even buying new guns makes no difference. Dwight is still a lousy shot.
The differences in skill between Dwight and Rosemary generate considerable conflict in their marriage. Dwight is an abusive husband and father––a lying, cheating alcoholic with almost no redeeming features. He's very much of the old school when it comes to manliness; he cannot stand the fact that his wife should be so much better than him at anything, especially a traditionally male pursuit like shooting. Rosemary's success is perceived by Dwight as a threat to his masculinity and the iron grip he maintains over the household.