Veto

A veto is an agreement between primary partners that either partner can require the other to end an outside relationship. In its strong form, the veto is unilateral and absolute: 'I have decided this needs to end' is sufficient, no further explanation is required. In softer forms, the veto is a structured request that triggers a deeper conversation, often with the right to require time-limited distance or specific changes before deciding whether to end the connection altogether.

Vetoes are widely criticised in modern polyamory writing, including by practitioners who themselves used them earlier in their journeys. The core objection is that a strong veto treats the outside partner as a person to whom no commitments are owed — their continued existence in the polycule is contingent on the primary's tolerance, with no participation in the decision. This can be devastating to receive and is structurally incompatible with treating that relationship as a real relationship between adults.

A more nuanced framing distinguishes veto from boundary. A partner can have personal boundaries that affect a relationship — 'I cannot continue sharing a household with you if you are dating someone who is actively unsafe' is a boundary about the speaker's own actions. A veto is a different shape — 'I am directing you to end that relationship' — and is a kind of relational instrument that most modern writers caution against using.

Where the veto retains defenders: in the very early stages of opening a previously-monogamous relationship, where neither partner has experience navigating polyamory and where the safety net of mutual veto can give one partner the courage to consent to the structure at all. Many couples who start with a mutual veto explicitly retire it after they have built more confidence in handling outside relationships.