Is ethical non-monogamy healthy?

The honest answer from the research is that consensual non-monogamy is not inherently more or less healthy than monogamy. Multiple studies comparing CNM and monogamous people find comparable relationship satisfaction, commitment, jealousy levels, and sexual satisfaction, and CNM people are often as conscientious or more so about safer-sex practices like testing and barrier use. There's no evidence base for the intuition that non-monogamy is psychologically damaging by nature.

Health lives in the practice, not the structure. The markers of healthy ENM are the markers of any healthy relationship, made explicit: genuine and ongoing consent from everyone involved, honest communication, agreements that are revisited rather than imposed, and treating every partner as a full person rather than a means to an end. Add the ENM-specific layer of sexual-health agreements, and you have the basic recipe.

The flip side is equally true: ENM practised badly is unhealthy in the same ways monogamy practised badly is — coercion, dishonesty, using a partner to avoid your own work, neglecting consent. 'Is ENM healthy?' has the same shape as 'are relationships healthy?' The structure is neutral; what people do inside it is what matters.