That is too simple to hold his wife to be responsible for his affair out of a marriage. You have to analyze a person from a lot of aspects including his wife’s role play in a marriage. How was he raised up? What was his attitude toward sex? What is his moral level in a society? What is his sex orientation? How much did he love her when they got marred? There are many conditional marriages and arranged ones. So ….. Don’t blame a “non - charming” wife. I even know someone who does not touch any woman even he is single. If you want to have an affair, go ahead, don’t blame the wife is too plain. I support guy’s contribution to boom our population by pregnanting more than one woman. You guys do a good job!