In her thoughtful Atlantic cover story on gay marriage (The Guide to Wedded Bliss, 5.22.13), Liz Mundy suggests that the “great gay marriage experiment” teaches us how to reinvent marriage so that it’s durable through the next century. Mundy reminds us that, although marriage has changed a lot from the “Father Knows Best” days, it is still burdened with old notions and habits about how men and women should behave — habits that are largely at odds with economic and practical realities.