The term "open marriage" came into common parlance with Nena and George O'Neill's 1972 book Open Marriage: A New Life Style for Couples. They didn't invent the concept, but they did articulate open marriage rules and offer advice about how to have a successful open marriage.
Similar to some of the guidelines for swinging, open marriages emphasize honesty and communication. Unlike the swinging lifestyle, however, open marriages allow for polyamory within the confines of a legally binding relationship. To make an open marriage successful in the 1970s - when the sexual revolution was going strong - couples had to take a leap, keep an open mind, and maybe hit up a certain type of club... together.
The O'Neills advocated open marriage as an alternative to traditional marriage, emphasizing choice and the ability to change. A husband and wife could maintain their relationship while engaging in new activities, experiences, and freedoms. The focus was on making a marriage work, albeit with some untraditional techniques.
According to their research, many individuals were struggling with the idea of traditional marriage. One woman told them, "I don't want to say yes, yes we are going to be in love forever. It's like saying, yes, yes you know the ocean - and the next wave is going to look like this one, but I can say it is worth the risk if I feel I can do something about it... it's not. 'I'm doing this because I've got to do it,' it's doing this because I chose to do it, and that's what it is, man is a thinking animal, therefore I am."
For the O'Neills, open marriage, as an alternative to the unrealistic and idealized form of marriage described here, took some of the pressure off the individuals and the marriage itself.
Sexual liberation and revolution in the 1960s and 1970s included everything from the rise of feminism, a heightened awareness of homosexuality, and the drive for women to control their own bodies. Alongside those movements, individuals and couples took part in swinging and open marriages, experimenting with new sexual freedoms.
There wasn't a lot of overlap in activities, however. Swinging and open marriage both had a "somewhat bureaucratized and decidedly unfestival-like quality" and participants rarely delved into "movements for such things as abortion reform or changing legislation pertaining to homosexuality." So the participants of open-marriage relationships were down to swap partners, but they weren't necessarily smashing the patriarchy or fighting for other civil and sexual liberties on a larger scale.
Open marriage wasn't just about heterosexual relationships. It wasn't even just about sexual relationships. Same-sex companionship for sex or for friendship was common in open marriages.
If one of the individuals in the marriage was curious about bisexual relationships, that was fair game too - as long as both parties agreed.
Threats to marriage and threats to health were influential on the decline of open marriage, with the AIDS crisis of the early 1980s weighing heavily on the latter. Sexually transmitted infections, especially AIDS, led to fewer open marriages and less swinging. The fact that many people in open relationships were not actively following the guidelines to a healthy open relationship made it harder for partners to trust each other.
One partner could be left as the sole caretaker for a spouse dying of AIDS, and for many of the open marriage participants that were pretty center-of-the-road, middle-class folks, this was a daunting potential future. Still, swinging and open marriages did not completely disappear.