When I first came out as a bisexual man, I sometimes heard responses like, "It's just a stepping stone between identifying as straight and identifying as gay," and, "See how you identify in five years." From that I learned that if a person does not fit in a neatly packaged place within the straight-gay binary, some people won't believe them, a fact that led me to wonder whether I was merely identifying as bisexual, and later queer, to hang on to a last shred of heterosexuality. With time I came to understand that the responses I got and the doubts I experienced were a result of stereotypes and other structural forces that favor monosexual identities -- that is, straight, lesbian, and gay identities as opposed to bisexual, pansexual, and queer ones. It's important to highlight that coming out can mean not only acknowledging one's same-sex attractions but navigating a society that does not fully understand identities that are neither straight nor gay.
People face numerous barriers to coming out and proclaiming an identity that does not fit the straight-gay binary; though some of the barriers are similar to those faced by lesbian and gay people, others are unique to non-monosexual people. There are numerous negative stereotypes about non-monosexual people, such as the myths that bisexual people have unstable identities, are prone to cheating, or don't really exist at all. There are few positive images of non-monosexual people; a relationship between two people in which one or both partners is bisexual, pansexual, or queer is nonetheless viewed as a straight, lesbian, or gay relationship. While "heterosexual," "lesbian," and "gay" each mean something specific, the English language lacks words that easily convey the kinds of nuanced identities that many non-monosexual people have (e.g., mostly attracted to the same sex but occasionally attracted to the opposite sex). As a result, some people are unaware that there are sexual orientations that they might be able to identify with besides heterosexuality, homosexuality, and 50-50 bisexuality. Heterosexual privilege can also contribute to the barriers: A person with mostly opposite-sex attractions but occasional same-sex attractions must give up her heterosexual privilege and risk discrimination and hostility if she is to acknowledge her same-sex attractions, even if such attractions never result in a relationship.
Structural resistance to non-monosexual identities may also be related to implications for monosexual people. Kenji Yoshino lays this out nicely in a legal article about bisexual erasure: Among other things, viewing sexual orientation as a spectrum may call into question some straight-, lesbian-, and gay-identified individuals' identities, which can be uncomfortable. (Just think of the ways in which people describe possible exceptions to a straight identity: "curious," "experimenting," "bromance," "I kissed a girl, and I liked it.") Even for a person who is 100-percent straight, the widespread acceptance of non-monosexual identities would affect perceptions of his sexual orientation, Yoshino notes; no longer would an opposite-sex crush or relationship establish that he is heterosexual. These concerns limit society's incentive to change its attitudes about identities that are neither straight nor gay; addressing the heterosexism at the root of these concerns will be important in creating change.
It is my hope that our society can remove barriers that keep people from genuinely identifying with and experiencing their sexual orientations, whatever they may be. When it comes to non-monosexual identities, I hope that better understanding the barriers to coming out with such identities can lead us to be aware of our assumptions, develop more effective language, and provide more affirmation of these identities. On that note, I want to emphasize that whatever combination of men, women, and genderqueer or genderless people a person is attracted to, and whatever proportion of a person's attractions any gender represents, is OK. I don't say this to be cliché but to encourage us to think about what that really means: recognizing and celebrating how people experience their sexuality, including in numerous ways that don't fit a binary.