One thing I've noticed with women who talk about their affairs is they are often at pains to praise their husbands...provider/nurturer attributes.
Women who have been interviewed anonymously and admit to affairs will say things like, "I won't tell my husband not to hurt him", or "he's a good man, and good for me and the kids", or "he's a provider and I am thankful for that". The unspoken implication is that they appreciate their husband's "beta" qualities, but do not find sexual satisfaction from them. And at a subconscious level-they will not see their husband as a good or worthy sire of their children genetically(now for women who cheat after their marriage is established and the children are definitely the hubbies, its more subconscious dissatisfaction) but are quite pleased with the providing and nurturing their husbands perform.
In short a woman can cheat and totally think she isn't contemptuous or spiting her husband, after all he's a good man and good provider, excellent father but he's not giving me what I want in the bedroom and/or he just isn't fit to sire my children genetically.
That is if you hold to this theory.