Those in the non-monogamous community, however, have a different (but equally magical) concept of what a unicorn is: It’s a person who is sexually and/or romantically involved with a couple.Ī unicorn may be someone who joins a couple for a threesome for one night, or it may be someone who regularly dates or even lives with both members of a couple. For many, the word “unicorn” conjures images of horse-like creatures with fancy rainbow manes and sparkly horns.