Ever notice your crushes all have one thing in common ― namely, the fact that they’re taken? Even if that’s with each other?

Whether your “type” is a married couple or a pair in a long-term relationship, researchers now think they know what’s going on with people whose romantic preference is “that one couple.”

In a paper published in Archives of Sexual Behaviour, author Sally W. Johnston, adjunct professor of anthropology and sociology at Seattle university, sought to find out why “some people experience attraction to two (or more) people in a preexisting relationship.”

Calling the phenomenon “understudied,” they also shared the term previously given to it by the Society for the Scientific Study of Sexuality ― it’s “symbiosexual attraction,” or “symbiosexuality.”

The 2021 definition of the term describes it as “the individual experience of sexual and/or romantic attraction to people in relationships.”

That doesn’t just have to be two people; it can be more. But the point is that symbiosexual people are attracted to “the relationship and/or energy shared between people” in established relationships.

The specific attraction to that dynamic makes it different to other sexualities, like plurisexualities (attraction to more than one gender).

Nor is it the same as polyamory, where one person may have multiple romantic and/or sexual relationships at once, but whose preference is for the option of those individual relationships and not for the dynamic another, separate relationship has.

So far as symbiosexual preferences go, a couple’s intimacy, looks, playfulness, relationship quality, and “gender and/or sexual queerness” all seemed to make them more attractive.

23% of people in the study said they’d felt a one-off attraction to a couple; almost 52% said they’d felt attracted to couples “a few times”; 24% shared they experienced attraction to couples sometimes or often.

That’s not a straightforward connection, though.

“While the term only implies a willingness or interest to engage in dynamics with couples and not (necessarily) an attraction to their preexisting relationship, the existence of the term both evidences symbiosexual attraction and discredits it.”

“Evoking notions of myth and fetish, the term unicorn perpetuates invalidation of and discrimination against people who seek these dynamics whether they are motivated by symbiosexual attraction or not,” the paper continues.

The same author published another paper this year on the “unicorn” phenomenon.