Black and white photo of a man kneeling over a woman on a bed in a dim room with brick wall
Key Takeaways
An open marriage is not a repair tool for an already-struggling relationship; it works as an extension of existing trust, not as a substitute for it.
The ethical difference between consensual non-monogamy and infidelity is consent and transparency, not the outward activity.
Contemporary CNM research — work by Moors, Conley, Haupert and colleagues — describes relationship satisfaction in openly negotiated arrangements as broadly comparable to that in monogamous ones.
Monogamy is an equally legitimate choice; the case for open marriage is not that it is better, only that it is a valid structure for couples who genuinely want it.
Legal definitions of adultery vary by jurisdiction and do not always map onto the ethical question of whether a specific arrangement is infidelitous.
Frequently Asked Questions
Is an open marriage a form of infidelity?
No, not in the ethical sense that most people mean by infidelity. Infidelity refers to sexual or romantic activity conducted behind a partner's back, without their knowledge or consent. An openly negotiated open marriage is the opposite of that by definition — both partners know and have agreed to the structure in advance. Legal definitions of adultery vary across jurisdictions and may not align with this ethical distinction, but the question of fidelity between two partners is a question about consent and transparency rather than about the act itself.
What is an open marriage, exactly?
An open marriage is a committed partnership in which both spouses have agreed that either or both of them may have sexual or romantic connections outside the marriage, on terms they negotiate together. The specifics vary widely: some couples prefer a strictly sexual scope, others incorporate emotional connection, and many operate with detailed agreements about what kinds of activity, disclosure, and boundaries apply. The term entered broader cultural awareness in the early 1970s and has been refined considerably since, particularly by contemporary CNM researchers and community educators.
Is open marriage a way to save a struggling relationship?
No. This is one of the most important honest statements that responsible writing on the topic makes early. Opening a relationship that already has unresolved conflict, resentment, or eroded trust tends to amplify those problems rather than resolve them. The couples who describe open arrangements as working over time are overwhelmingly couples whose partnership was already stable before they opened it. Monogamy remains an entirely legitimate choice for couples who prefer it, and it is often the right answer when a relationship is in difficulty.
The honest starting point on this topic is the one that the legacy version of this article never quite reached: an open marriage is not a fix for a struggling relationship. It works as an extension of an already-solid partnership, not as a repair mechanism for one in distress. Couples who open a relationship that is already carrying unresolved resentment or eroded trust tend to surface those problems rather than resolve them — and the open arrangement often takes the blame for damage that predated it. The couples who describe open marriage as working, often for years, are almost always couples whose marriage was already functioning well before the question of opening it came up.
That gate set, the question the title raises — is an open marriage infidelity? — has a cleaner answer than it is usually given.
The Line Consent Draws
Infidelity, in the ethical sense, is sexual or romantic activity conducted behind a partner's back, without their knowledge or consent. The secrecy is not an incidental feature — it is the defining one. What makes an affair an affair is that the partner is being deceived. An openly negotiated open marriage inverts that structure entirely: both partners know, both partners have agreed, and the terms of what either person may do have been discussed explicitly in advance.
Once that distinction is drawn clearly, the question collapses. Two adults who have agreed on the structure of their own partnership are not betraying each other by following the agreement they made together. That is the ethical answer, and it holds independent of how any particular jurisdiction happens to define adultery in law.
Where the Legal Picture Complicates Things
Legal definitions of adultery vary considerably across jurisdictions. A small number of places still treat any non-marital sexual activity as adultery for certain legal purposes, regardless of whether both spouses consented. That is a separate question from the ethical one. Couples considering an open arrangement in a jurisdiction where adultery carries legal consequences may want to understand the local landscape — particularly as it relates to divorce proceedings, custody, or other family-law matters — but the legal question is not the same as the question of fidelity between two partners.
What Contemporary Research Describes
The post-2020 CNM research literature, including work by Moors, Conley, Haupert and other researchers publishing in places like the Journal of Sex Research and the Archives of Sexual Behavior, has described adults in consensual non-monogamous relationships as reporting relationship satisfaction and psychological well-being broadly comparable to those in monogamous relationships — provided the arrangement is genuinely negotiated rather than coerced, and provided the underlying relationship was healthy before the opening. The research does not claim open marriage is better than monogamy. It describes a population of adults for whom this structure works, on the terms they have chosen.
The structure that seems to hold up is not complicated in the abstract, though it takes work to maintain. Both partners had separately decided they wanted this before any external activity began. The specifics were discussed in concrete detail, not left as a vague understanding. There is a regular check-in built into the rhythm of the relationship so that adjustments happen deliberately, not as reactions to something going wrong. And both partners still treat the core partnership as the primary commitment rather than as one option among many.
— Married and partnered couples on Swing.com in openly negotiated arrangements
Monogamy as an Equally Legitimate Choice
The case for consensual non-monogamy is not that it is better than monogamy. The two structures meet different needs, reflect different temperaments, and require different kinds of emotional work. Monogamy is a legitimate choice made by a large majority of adults for reasons that are entirely their own. CNM is a legitimate choice made by a smaller group for reasons that are equally their own. The substantive ethical question — in either structure — is whether the arrangement was genuinely chosen, whether it is honestly maintained, and whether the specific terms are clear to both people.
Why the Framing Question Matters
The reason the "is it infidelity" question keeps being asked is partly a vocabulary problem. Words like adultery and infidelity have historical weight that does not always map cleanly onto negotiated modern arrangements. The more precise language the contemporary community has developed — consensual non-monogamy, ethical non-monogamy, polyamory, open marriage, soft swap, full swap — exists in part to describe specific structures that older words flatten together. Couples who understand the distinctions tend to have cleaner conversations about what they actually want.
Where Thoughtful Exploration Starts
For couples whose partnership is already stable and who are seriously considering opening it, the honest starting steps are unglamorous: extended conversation before any external activity, explicit agreement on the specific terms, a shared understanding of how disclosure and check-ins will work, and a shared commitment to treat the first phase as provisional rather than permanent. Community platforms like Swing.com offer verified profiles, structured search, and group messaging that allow couples to establish expectations before meeting anyone in person — but the more important infrastructure is the one inside the marriage itself.
Swing Editorial··4 min read