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Open marriage typically refers to a marriage in which the partners agree that each may engage in extramarital sexual relationships, without this being regarded as infidelity. There are many different styles of open marriage (such as swinging and polyamory), each with the partners having varying levels of input on their spouse's activities.
History of the term
The origins of the term remain obscure. Researchers in the 1960s used the term "open marriage" to describe individual freedom in choosing marriage partners. A "closed marriage" said individuals had to marry someone based on social conventions and proscriptions; "open marriage" meant individuals could choose to marry someone based on personal preferences.
Nena O'Neill and George O'Neill changed the meaning of the term with the 1972 publication of their book Open Marriage, which sold over 1.5 million copies. The O'Neills conceived open marriage as one in which each partner has room for personal growth and can develop outside friendships. Most chapters in the book dealt with non-controversial approaches to revitalizing marriage in areas of trust, role flexibility, communication, identity, and equality. Chapter 16, entitled "Love Without Jealousy", devoted 20 pages to the proposition that an open marriage could include some forms of sexuality with other partners. These concepts entered the cultural consciousness and the term "open marriage" became a synonym for sexually non-monogamous marriage—much to the regret of the O'Neills.
In her 1977 book, The Marriage Premise, Nena O'Neill advocated sexual fidelity in the chapter with that same name. That year, she told the New York Times, "The whole area of extramarital sex is touchy. I don't think we ever saw it as a concept for the majority, and certainly it has not proved to be." However, by then, the use of the term "open marriage" to mean sexually non-monogamous marriage was in widespread use.
George O'Neill died in 1980; Nena died in 2006.
The impact of open marriage on relationships varies across couples. Some couples report high levels of marital satisfaction and have long-lasting open marriages. Other couples drop out of the open marriage lifestyle and return to sexual monogamy. These couples may continue to believe open marriage is a valid way of life, just not for them. Still, other couples experience serious problems and claim open marriage contributed to their divorces.
Couples involved in open marriages or relationships typically adopt a set of ground rules to guide their activities. Ground rules in relationships allow partners to coordinate their behaviors, so they achieve shared goals with fewer conflicts. Some ground rules are universal in the sense that they apply to virtually all relationships in a particular culture. Other ground rules apply to particular kinds of relationships, such as friendships or marriages. Still other ground rules are designed to manage romantic rivalry and jealousy. The ground rules adopted by sexually monogamous couples tend to prevent behaviors that are viewed as acts of infidelity. The ground rules adopted by sexually open couples tend to prohibit behaviors that provoke jealousy or sexual health concerns. Partners may change the ground rules of their relationships over time. One example of a changing ground rule includes where a married couple decides to separate. Without divorcing, they are still legally married. However, they may choose to continue cohabitation.
Open marriage styles
Couples in open marriages may prefer different kinds of extramarital relationships. Couples who prefer extramarital relationships emphasizing love and emotional involvement have a polyamorous style of open marriage. Couples who prefer extramarital relationships emphasizing sexual gratification and recreational friendships have a Swinging style of open marriage. These distinctions may depend on psychological factors such as sociosexuality and may contribute to the formation of separate Polyamory and Swinging communities. Despite their distinctions, however, all open marriages share common issues: the lack of social acceptance, the need to maintain the health of their relationship and avoid neglect, and the need to manage jealous rivalry.
Many open couples maintain rules forbidding emotional attachment, extramarital children, extramarital sex in the marital bed, extramarital sex with those known to both partners, or extramarital sex requiring use of barrier contraception.
Some open marriages are one-sided. Some situations giving rise to this are where the libidos of partners differ greatly, or illness renders one partner incapable of, or no longer desiring, sex. The couple may remain together while one partner seeks out sexual gratification as he/she sees fit. The difference between these situations and a cheating situation is that both partners in the marriage are aware of, and agree to the arrangement.
Couples in open marriage may expose themselves to situations that could provoke jealousy. Most couples in open marriages report experiencing jealousy at some point during their marriage. Ground rules are one way to help manage jealousy in open relationships. However, ground rules may not be sufficient. Couples in open marriages may benefit from a general understanding of jealousy and how to cope with it.
Open marriage acceptance
Surveys show large majorities of people disapprove of extramarital sexual activity. A few studies show people specifically disapprove of open marriages. Critics have put forward moral, medical, and psychological objections to open marriages. The lack of social acceptance places pressure on couples to hide their open marriages from family, friends, and colleagues. This may limit their social support network.
Many of those disapproving with open marriage speak up against it because of "religious and moral reasons" making these groups differ from those agreeing. Those that have admitted to an open marriage or any "informal arrangement", "probably is 4% to 9% in U.S. adults". The term of open marriage isn't really something just "invented". Now we are starting to see a different form of monogamy that is "open to variety of lovers" and shares "feelings", "needs", and "desires". This sexual practice isn't new, we have been seeing these styles of openness in the 1960 through the 70s with the sexual openness of "swingers".
The practice of extramarital sex is often illegal in jurisdictions where adultery is illegal, regardless of whether the partner(s) has given their consent. Open marriage is not the same thing as polygamy, where sexual relationships are not necessarily contemplated, but rather one can have more than one simultaneous spouse, which is said to protect individual and marital property rights.
Incidence of open marriage
The incidence of open marriage is the frequency with which open marriage occurs. Several definitional issues complicate attempts to determine the incidence of open marriage. People sometimes claim to have open marriages when their spouses would not agree. Couples may agree to allow extramarital sex but never actually engage in extramarital sex. Some researchers define open marriages in narrow terms. Despite these difficulties, researchers have estimated that between 1.7 percent and 6 percent of married people are involved in open marriages. The incidence of open marriage has remained relatively stable over the last two generations.
Notable people in open marriages
- Jenny Block, author of Open: Love, Sex and Life in an Open Marriage
- Thomas Braden, journalist
- Margaret Cho, actress and comedian
- Misha Collins, actor and wife Vicki Vantoch, author 
- Bob Crane, actor and Sigrid Valdis, actress
- Robert Crumb and Aline Crumb, cartoonists
- Ruby Dee and Ossie Davis
- Denholm Elliott, actor
- Havelock Ellis, sexologist
- Erica Jong, author
- Larry King, talk show host and Shawn Southwick, singer
- Alfred Kinsey, sexologist and wife Clara Bracken McMillen
- Charles Laughton, actor, and Elsa Lanchester, actress
- Shirley MacLaine, actress
- Edna St. Vincent Millay, American poet
- Mo'Nique, actress/comedian
- Amanda Palmer, American performer and Neil Gaiman, English author
- Ayn Rand, novelist, philosopher, playwright, and screenwriter
- Robert Rimmer, author of The Harrad Experiment.
- Vita Sackville-West, author, and husband Harold Nicolson
- Margaret Sanger, founder of Planned Parenthood
- Will Smith, actor and wife Jada Pinkett Smith
- Eliezer Yudkowsky, AI researcher and blogger
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