In a fifth of marriages, wives now out-earn their husbands. More women are graduating from college than men. The workforce now skews female, and men have been hit harder by the recession, forcing women into the breadwinner role. Several of these tipping points have been celebrated as a move toward greater equality and a boon for men, who for the first time, gain economically from marriage. ... Yet almost three decades after Mr. Mom parodied such role reversal, many couples still struggle emotionally with their “new” identities, often in ways they’re ashamed to admit. Ways that society could better address, say marriage experts.