One-penis policy (OPP)

Also: OPP, one-vagina policy (OVP), one-dick policy

A controversial agreement in which a man permits his woman partner to have other women partners but not other men. Widely critiqued as enforcing male insecurity and biphobia rather than any coherent ethic.

1 min read · Reviewed 2026-05-24

A one-penis policy is a rule, almost always set by a man in a mixed-gender relationship, that his woman partner may date or play with other women but not with other men — so there is only ever 'one penis' in the relationship's orbit. The mirror-image one-vagina policy exists but is far less common. The arrangement is most associated with couples opening up from monogamy, and with the LifeStyle and hotwife scenes.

OPP is one of the most heavily critiqued structures in contemporary non-monogamy writing. The standard objections are that it treats women partners as less threatening (rooted in a view of queer women's relationships as not 'real'), that it manages the man's insecurity by constraining everyone else rather than by his own work, and that it is frequently biphobic — erasing the legitimacy of a bisexual woman's attraction to men. It also tends to set up the very dynamic it fears, by making the rule itself a source of resentment.

Defenders frame it as a transitional safety rail while a nervous partner adjusts. Even sympathetic writers generally argue that if it's used at all it should be named honestly as one person's insecurity-management, be explicitly temporary, and be retired as the relationship matures — rather than dressed up as a principled ethic.

Where this term fits in the wider picture

Ethical non-monogamy is a network of overlapping practices, identities, and structures — and One-penis policy (OPP) connects to several of them. The neighbouring terms below show how this one sits alongside the rest of the vocabulary practitioners actually use; the guide at the end is the longer-form treatment of the same territory.

Closely-related vocabulary

Veto
An agreement granting one partner unilateral power to end another of their partner's outside relationships — common as a structure, widely criticised in its strong form.
Couple privilege
The structural advantages an established couple holds in a polycule — legal, financial, social, practical — by virtue of being a recognised couple.
Boundary
A statement about yourself — what you will or will not do in given circumstances — distinguished from a rule, which is a statement about what another person must do.
Agreement
An explicit, negotiated understanding between partners about how the relationship will operate — distinguished from rules in modern polyamory writing by being mutual rather than imposed.
Open relationship
A committed primary relationship in which the partners have agreed that outside sexual, and sometimes romantic, connections are allowed within negotiated terms.

Questions practitioners actually ask about this

Continue reading

The longer treatment of this territory is in the guide Boundaries vs rules — and why the difference matters — Why most 'rules' between partners are really boundaries about yourself — and how confusing the two reliably undermines a polycule.

New to ethical non-monogamy? Start with the glossary for vocabulary, the structures index for the named relationship configurations practitioners actually use, and the guides for longer-form treatment of the common questions.