Bisexuality exists and is a recognized sexual orientation. As the American Psychological Association explains:

The term “bisexual” is used to describe a person who experiences emotional, romantic and/or sexual attractions to, or engages in romantic or sexual relationships with, more than one sex or gender. The Centers for Disease Control and Prevention reported in a 2016 publication that 1.3 percent of women and 1.9 percent of men said they were “homosexual, gay, or lesbian,” and that 5.5 percent of women and 2 percent of men said they were bisexual. These finding indicate that bisexual people may comprise the largest single group in the LGB community for both women and men. Nevertheless, many believe that bisexuality does not really exist, and bisexual people experience bi-invisibility or erasure and bi-negativity from both the lesbian and gay communities and the heterosexual community, which may explain evidence suggesting higher rates of health disparities bisexuals experience compared to either.

Additional research found that bisexual people are significantly less candid about their sexual orientation with family and friends.

If your partner tells you they are bisexual, you may experience any number of emotions, from shock and anger, to confusion and curiosty. Bisexual attractions are complex and may lean more heavily toward one particular gender. It may take time for you and your bisexual partner to assess the balance of their sexual attractions, but it may be possible for straight/bisexual relationships to work successfully between understanding partners. Redefining your relationship may involve a great deal of patience, creativity and open-mindedness, but the bond between straight/bi partners can make for fulfilling partnerships. For more information about bisexuality, check out bi.org.