Unicorn hunting

Unicorn hunting is the practice by two people who are in a relationship, usually a heterosexual couple, of seeking a third partner for the relationship temporarily or permanently, usually a bisexual—though occasionally, a lesbian—woman, either to join a threesome or to start a polyamorous relationship. The practice is generally viewed negatively by the polyamorous and LGBT community as a form of fetishisation.

Term
The term "unicorn hunting" comes from, comparable with the legendary creature, how rare a bisexual woman willing to join an existing couple is, as well as their conditions, which can include relational exclusivity (contrary to open relationships with other people), equal attraction to both partners or interest in only having group sex. Likewise, lesbians tend to reject these offers for similar reasons, with their lack of interest in men in addition to that. Its use might have started in the 1970s by swinger communities of the time to describe bisexual women available to have a threesome with a heterosexual couple.

Practice
Unicorn hunting consists of two people in a relationship, usually a heterosexual couple of a man and a woman, seeking a bisexual woman for the relationship, either to join a threesome or to form a polyamorous relationship. A unicorn polyamory is different from a triad or throuple relationship in that in a throuple, the three members are primary partners, while a "unicorn" joins an existing couple. In a triad, rules are usually agreed upon all members, whereas in unicorn polyamory, it is assumed that the couple makes the rules, while the unicorn has to follow them. It usually considers the couple as primary partners and the unicorn as the secondary partner, since if the unicorn consents to joining their existing relationship, the unicorn also accepts their conditions. As such, the practice is seen negatively by the polyamorous and LGBT communities due to the power imbalance in the relationship, and is considered to contribute to the fetishisation of bisexual women.

Couples looking for a third partner might do it by using dating apps or websites. Vogue India also cited a distinction between "hunters" and "retrievers", where in the latter women find a person for predatory men.