"Mating preferences, after all, are driven not only by attraction but by attainability."
James Taranto at Best of the Web: "Rich Woman, Poor Man: Why do female breadwinners tend to have unhappy marriages?":
Why are men averse to higher-income women? Perhaps because they understand that women are averse to lower-income men. Mating preferences, after all, are driven not only by attraction but by attainability. In theory all men should be attracted to supermodels; in practice few would have the confidence to ask one out.
If, as Mundy suggests, female breadwinners find it a "struggle" to remain attracted to their husbands, then avoiding such a marriage seems a wise defensive move for a man. If the evolutionary psychologists are right, it's a relatively easy one to make, since a woman's earning power would not exert much emotional or sexual pull on a man.