Duogamous

Duogamy refers to a bisexual individual who has two exclusive partners, one of each (binary) gender. It's when an individual has one male and one female relationship.

The word duogamous is mentioned in the Bisexual Manifesto in 1990. Because of identity elitism, bisexuality is commonly erased by biphobes for not practicing duogamy, as if they were not truly bisexuals.