Monogamy and non-monogamy

Anna Kelberg

Throughout history, people have structured their sexual relationships in different ways. Though they may seem like a 21 st  Century concept, non-monogamous relationships are not an invention of our generation (ref.1). Though usually discussed in hushed voices and after the children had gone to bed, parents of our parents often knew somebody who lived in an open relationship, had multiple lovers or even attended an orgy. In the last decade, non-monogamy seems to be on the rise, or perhaps has just become less of a taboo topic. However, great confusion exists around the concepts and labels and my goal for this article is to explain the most common sexual relationship structures.

My one and only: monogamous relationships

Monogamous relationships are those that follow the rule of no sexual or romantic relationships outside of the main partnership (ref.2). Despite worldwide marriage rates declining over the last two decades, about 85 percent of Americans and Europeans are still projected to get married (ref.3) or live in a “marriage-like” relationship (ref.4).

The concept of monogamy seems straightforward and uncomplicated at first, but, like any relationship, it is filled with nuance. These two hypothetical situations, about men named Mark and Peter, can help us understand some of these nuances. Mark, while married multiple times, was faithful to each of his wives while he was married to them. When he was not married, however, he believed that it was fine to date as many partners as he wanted – though he never gave false promises to his girlfriends. Peter met his wife at school and they had a long and generally happy marriage until she died. Now, Peter is alone and plans to keep his wedding day vow to be faithful to her, despite the fact that she has since passed away. In other words, you can be monogamous for a lifetime (ref.5) or only during certain periods of your life (ref.5,6).  But is it as straightforward as it looks? Monogamy is, after all, a social construct, while what matters
is inside the couple’s relationship.  Would Peter’s wife consider him faithful if she found a stash of porn on his computer?  Or would any of Mark’s later wives throw down the gauntlet if he screamed the previous wife’s name in the heat of passion?  Not even the clearest type of relationship can be painted in black and white, and you can read about the grey areas of monogamy in my article iCheat.


Non-monogamy can be consensual or not, the main difference being whether or not your partner knows and approves of your extra-dyadic relationship.

Secret sex: Infidelity

Most people consider physical sex with someone else without one’s partner’s explicit consent to violate the monogamy agreement. When this agreement is broken, the other partner usually ends up feeling betrayed (ref. 7, 8, 9). The main question is: What behaviors constitute unfaithfulness? Some partners allow room within their monogamous relationships for innocent flirtation or online entertainment like porn or sex chats, while others stick to more strict definition of boundaries.

Another nuance of infidelity is that it can be sexual, emotional, or both (ref. 9, 10, 11). Usually the focus of infidelity is on the sexual act – in one study where respondents were asked to define what sexual infidelity was, most emphasized specifically sexual activity (Ref.10). However, a non-sexual but romantic connection to a lover can be just as devastating as sexual infidelity is to one’s partner and relationship.

In contrast to open relationships, where partners are in agreement regarding non- monogamy, infidelity is a common cause of divorce (ref 12). However, it is the break of trust, not the nonmonogamy itself, that makes sexual infidelity so disruptive to the marriage (ref. 13), as trust is believed by theorists to be one of the most important components of relationship quality (ref.14).

I am fine with that: consensual non-monogamy

While cheating without one’s partner’s knowledge is far more common in society (estimates vary between 20% and 70% of all people have cheated on their partner without that partner’s consent. See my article "Cheater, cheater, pumpkin eater for more details), some couples choose to openly discuss their extra-marital sexual needs and desires. Although it is estimated that only about 4-5% of the population choose to “talk about it” (ref.15), the nuances and differences of these agreed upon relationships vary greatly.


Swinging is probably the most commonly portrayed form of open relationships in the media. Swingers are couples who engage in sexual relationships with others, often in close proximity at a party, sex club or in other social setting (ref.16). An important element of a swinging relationship is that the primary couple views swinging as something that they do as a couple, treating it like a shared pastime (ref.15). Participants of a swinging party or convention have a common understanding that they are not monogamous (ref.15) and may engage in a variety of non-monogamous behaviors. These include exchanging partners with another couple for inviting a third person to have sex with the couple (ref.15, 17). In any case, partners who swing can separate sex and love, as they allow only sex and not love to be shared outside their couple (ref.18).

Open relationships

An open relationship is an arrangement whereby the partners allow each other to seek sexual relationships independently from one another: “We are together, but I have my lover and you have your lover.” These relationships outside the main relationship usually are neither romantic nor loving, though differ from swinging. In contrast to swingers, who often have sex with other partners while their partners are present, those in open relationships pursue sexual experiences independently from their main partner (ref.15).


Unlike swingers, polyamorous individuals are more likely to describe their multiple relationships as having a romantic or emotional component, rather than being strictly sexual (ref.20). Although polyamorous individuals typically reject sexual and emotional exclusivity, these relationships often involve explicitly negotiated agreements about what types of extra-dyadic interactions are permitted by each partner. For example, partners may agree that it is acceptable for an individual to love both their partner and their lover, but at night that individual should always be with their partner. For some, polyamory means that having unprotected sex is permitted with one person, but not the others (ref.21).  Some polyamorists reject any relationship rules and emphasize the importance of individual freedom, communication, and ongoing negotiation (ref.18).

There are multiple kinds of polyamorous relationships. An individual may choose to partner with multiple people, or two members of a couple may date a third, also known as a triad. Some couples may even evolve into a relationship with another couple, known as a quad, or become a part of networks of people involved in various configurations with one another (ref.19).

It is tempting to classify romantic relationships into strict frames of monogamy and non- monogamy, though reality is complex and often has unclear and fluid boundaries. Dividing lines between different forms of relationship structures are blurry (ref.22) and should be perceived as generalized trends with various exceptions.

When it comes to relationships, we all have been influenced by personal experiences and social constructs.  And I can imagine that reading this article, it would be hard not to pass some judgement on what feels right or wrong.   Studying this fascinating field, I never stop being amazed at the diversity of choices that people make in their efforts to balance their personal and relationship needs. And I have encountered plenty of happy and unhappy couples in each of the relationships described above.  While the topic of happiness deserves a separate blog, couples that constantly work on their relationships fair better than those who leave the monogamy topic unattended.


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