In the 1950s there was a fair amount of "wink, wink" tolerance for a gap between the monogamy ideal and reality. The conservative 1980s were more about regulating behavior; religious social conservatives not only wanted us to act as if we were monogamous, they wanted us to be monogamous. Monogamy became a stricter social ethic.
But the reality is that a fair number of spouses cheat, and we forbid cheating. So, we end up with what I call the "shocking banality" of infidelity: It happens all the time and we're shocked by it all the time.
When did we begin to see an opening up of non-monogamy in marriage?
My argument is that in the 1970s free love and non-monogamy had a certain chic to them, but they didn't have solid foundations in demography, economy, or technology.
Today, the idea of openly non-monogamous marriages has no political chic to it, but it does have a more solid foundation in demography (we live longer and are healthier than ever), economy (women earn their own paycheck, and don't rely on the sexual contract in marriage for their meal ticket), and technology (we're connected to people more than ever).
So marital monogamy is under greater stress today. And I think it's being deliberately rethought and re-evaluated by a post-romantic generation that sees the main function of marriage as friendship, an establishment of a home base -- not sexual passion and fidelity, per se.
In the past, people married for money, order, family, and having babies. Today we seem more apt to say we marry for love. Yet statistics show we marry in our own social class and race. What are we really marrying for?
Today we are more inclined to marry partners than lovers. The majority of unmarried Americans say they want to marry a soul mate, according to Gallup research. It's an interesting goal, because it's not specifically a romantic love that we're envisioning. "Soul mate" can apply to any number of relationships, from friend to colleague to spouse. Maybe we want marriages that are intimate, but not romantic.
From what I understand, more people are marrying their best friend, but this does not bode well for marriages. That best friend/spouse is expected to be all things for us.
Men and women have the same opportunities and life experiences more than ever before; we're more similar and comradely toward each other. All of those things are victories, and upsides of feminism. The bad news is that a marriage today can slide too much into a partnership or a co-parenting arrangement, and lose the intimacy that comes from a sense of mystery or difference.
How does non-monogamy fit into the future of marriage?
More marriages will have a conversation about monogamy, rather than just assuming it is the default. It seems to me that non-monogamy might become a more accepted option, much as premarital sex has shifted from largely scorned to widely tolerated today.