Adding a Third Person May Strengthen a Couple — but What About the New Partner?

Couples who actively search for a third person to join their romantic or sexual relationship often report stronger bonds and better communication with each other, according to new research. Yet the same study finds that the newcomer’s needs and desires are frequently pushed into the background.

The paper, titled Searching for a Third: Couples’ Experiences of Unicorn Pursuit, Desire, and Ethical Tensions, adds to a small but growing body of research on consensual non-monogamy. Published in Psychology & Sexuality, the study explores both the perceived benefits for established couples and the ethical tensions surrounding the person invited into the relationship.

The research focuses on consensual non-monogamy, in which partners agree that romantic or sexual involvement with others is permitted. One increasingly visible arrangement involves an established couple searching for a third partner, informally known as a “unicorn,” to join them.

How unicorn hunting typically works

In popular culture and many online communities, unicorns are often imagined as bisexual women willing to date or have sex with both members of a couple. Researchers note that this image shapes expectations, although people of various genders can occupy the role.

Polyamorous and non-monogamous communities have long criticized so-called unicorn hunting. Critics argue that some couples treat the third person as a disposable accessory while maintaining a rigid hierarchy that keeps the original relationship firmly above the new connection.

To examine these dynamics, researchers led by Alena Bondarchuk-Mclaughlin of La Trobe University in Melbourne surveyed 80 people. All participants were either currently part of a couple searching for a third person or had done so previously, and they answered open-ended questions about their goals and experiences.

What couples say they are seeking

When describing their ideal third partner, most respondents said they wanted a woman, with many specifically mentioning a bisexual woman. However, nearly a quarter said gender did not matter, while others preferred men, other couples or emphasized characteristics such as kindness and open-mindedness.

Researchers coded the written responses into four themes: desired characteristics of the third person, effects on the existing couple’s relationship, preferred relationship dynamics and what actually occurred during real encounters. This approach revealed a consistent gap between fantasy and reality.

Most couples imagined a primarily sexual relationship with the third person, centered on fulfilling fantasies, introducing novelty and increasing their own shared pleasure. Only about 40% of respondents said they wanted a deeper emotional connection, such as friendship, ongoing dating or cohabitation.

Impact on the existing relationship

Despite the ethical tensions surrounding the practice, nearly 80% of participants said that searching for a third partner improved their relationship with their primary partner. They described better communication about sexual desires, clearer boundaries and greater trust after openly discussing their fantasies.

Some couples reported that simply discussing the possibility of involving another person made them feel closer. Sharing passwords on dating apps, negotiating rules for meeting other people and debriefing after dates were among the experiences participants described as strengthening their connection.

A small minority, however, reported negative consequences, including conflict, pressure and feelings of betrayal. In these cases, the search appeared alongside deeper relationship difficulties, including unresolved jealousy and mismatched expectations about non-monogamy.

The missing voice of the third person

One of the most striking findings was how rarely respondents mentioned the third person’s own desires or wellbeing. Only a small proportion explicitly stated that the third partner’s pleasure, comfort or consent was central to their ideal arrangement.

Some couples openly described the third person as a way to address perceived gaps in their existing relationship, improve their sex life or satisfy one partner’s particular needs. The authors note that this instrumental approach risks turning the “unicorn” into a resource rather than treating them as a fully equal partner.

When discussing their actual experiences, many respondents described one-off encounters or short-term sexual arrangements. Only around a quarter reported developing longer-term emotional or social relationships with a third person, while relatively few described sustained efforts to center that individual’s feelings.

Why unicorns are hard to find

Almost half of the participants said they struggled to find a willing and compatible third partner. Many reported a shortage of interested people, incompatible expectations or repeated misunderstandings during conversations and dates.

The researchers suggest that some of these difficulties may arise from how couples frame their search, particularly when the third person is approached more like a service provider than a participant in a mutual relationship. When a couple expects strict rules and hierarchy while the other person wants autonomy and care, disappointment is more likely.

Experts in consensual non-monogamy increasingly encourage couples to treat any third partner as an independent individual with their own needs and boundaries rather than as an addition to an existing pair. This includes being willing to negotiate, recognizing potential power imbalances and accepting that the established couple may also need to adjust their expectations.

Limits of the current research

The study relied on self-reported written responses from a relatively small, self-selected sample of 80 participants, meaning the findings cannot be generalized to all couples practicing consensual non-monogamy. The survey also focused exclusively on people within established couples, leaving the perspectives of the “unicorns” themselves unexplored.

Researchers acknowledge that information about important factors, including the genders of the couples and their cultural backgrounds, was limited. A survey prompt that included a “bisexual woman” as an example may also have encouraged participants to use that label, potentially influencing the responses.

Future research, the authors argue, should directly include the perspectives of third partners and follow these relationships over time. Such studies could help identify which practices support ethical and mutually satisfying arrangements and which patterns are more likely to result in harm or emotional strain.

As consensual non-monogamy and other relationship structures become increasingly visible, the findings highlight the importance of looking beyond whether an arrangement benefits the original couple. Communication and consent may need to account equally for the person entering the relationship, particularly when an established pair already holds greater power within the dynamic.

Article prepared by Victoria Caldwell.