Infidelity

Infidelity can shatter a marriage. Cheating and lying about it is almost always a crisis in a relationship. Research shows that cheating is cited as a reason for splitting up in 40% of divorces.

For some couples, non-monogamy is a choice. In open or polyamorous marriages, the partners agree to have emotional or sexual relationships with other people. They set rules and expectations for the relationships and try to be honest about what's going on in and out of the primary marriage. 

Open marriages are complicated, and they don't work for every couple that tries it. Some people open up a marriage for the wrong reasons, such as letting a partner openly cheat rather than lying about it. Other times, a partner may fall in love with an outside partner and want to pursue that relationship more deeply. 

For other couples, polyamory brings sexual or emotional satisfaction they won't get in a monogamous relationship. Their marriages are strong, happy, and long-lasting. 

Learn more about open marriage and why it might work for some couples. 

Types of non-monogamy

There are a lot of ways couples engage with additional partners. Cheating or non-consensual non-monogamy is very common. Having sex with people outside your primary relationship without telling your partner is usually distressing. The deception and infidelity pack an emotional punch. Not all couples can overcome that. In addition, you may run the risk of bringing home a sexually transmitted infection from such a relationship. 

Other couples choose to have relationships with additional people. They go into it knowing what their expectations are, and they avoid deceit or dishonesty. They are upfront about their feelings and try to be sensitive to one another's needs. 

There are several different forms that non-monogamy can take.

Open marriages 

In an open marriage, the couple agrees to sexual contact with other partners. Often, it's a situation where both members of a couple have sex with other partners together. Other couples prefer to have sexual adventures separately. The primary relationship is their main emotional focus. Most of the outside relationships are limited to sex without a deep emotional commitment.

Swinging

Swinging is a term for when a couple engages in partner-swapping with other couples or invites additional people to have group sex with them. They may go to sex clubs or swingers' parties to meet like-minded people. Swinging tends to be about sexual gratification for both people in the couple. They aren't looking for long-term relationships outside their marriage, though they may become friends with their swinging partners.

Monagam-ish 

This is a pop-culture term popularized by sex writer Dan Savage. Some couples agree to have sexual contact with others under very specific, pre-defined circumstances. They are honest about their personal boundaries and try to stay within them. They don't typically seek out other committed relationships. The sexual encounters are brief and non-committed.

Polyamory

Polyamorous couples look for lasting relationships outside their primary relationship. The parameters vary from couple to couple. Some couples keep their outside relationships separate from their primary relationship. Others introduce their additional partners to their primary partners. Typically, all the people involved in polyamorous relationships are aware of the situation, and they consent to everything that happens.

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How many open marriages end in divorce?

Non-monogamous marriages are as varied as monogamous marriages. They don't follow a set pattern. There is no sure way to predict if a non-monogamous marriage will last or if the partners will split up. 

By some estimates, as many as 20% of Americans engage in some kind of non-monogamy during their lives.  Studies suggest that 4%-5% of couples in the United States are non-monogamous. There is little published data on how many of these couples eventually divorce. Their divorce rates may be similar to monogamous couples. 

In some situations, non-monogamy is beneficial for both people in the primary relationship. This is particularly true when both people are enthusiastic about being non-monogamous. When they have solid communication and are good at being open and honest, they can navigate multiple relationships without issues. They may even be happier than monogamous couples who don't have the same level of communication and trust.‌

In other cases, couples begin non-monogamy with different expectations and different desires. One partner may suggest an open relationship rather than cheating on their main partner. If the other person only goes along with it to prevent divorce, the open relationship may not be a satisfactory experience. Divorce might be an outcome in the end.

Choosing a non-monogamous relationship can be very rewarding if both partners are committed to it. For couples who don't both embrace the choice, it might be the decision that ends their marriage.