Compared to monogamous relationships, consensual non-monogamous (CNM) relationships are stigmatized. Similarly, compared to heterosexual individuals, gay men are perceived to have more promiscuous and less committed romantic relationships. Hence, CNM and male same-sex relationships are potential targets of dehumanization (i.e., denied traits considered unique of human beings). We tested the impact of monogamy and sexual orientation on dehumanization, and examined whether CNM (vs. monogamous) and same-sex (vs. heterosexual) partners are dehumanized through the attribution of primary (non-uniquely human) and secondary (uniquely human) emotions. A sample of heterosexual young adults (N = 585, 455 women; Mage = 25.55, SD = 7.48) in three European countries – Croatia, Italy, and Portugal – attributed primary and secondary emotions to four groups: (a) monogamous heterosexual partners, (b) CNM heterosexual partners, (c) monogamous same-sex male partners, and (d) CNM same-sex male partners. Results showed that uniquely human emotions were attributed less to CNM than to monogamous partners, and this happened regardless of sexual orientation. Furthermore, CNM same-sex and CNM heterosexual partners were evaluated similarly. This pattern of results was consistent across countries. The implication of these findings for social policies and sexual rights are discussed