Monogamous

Monogamy is the act of being in or desiring an exclusive relationship between exactly two people. Neither participants of a monogamous relationship are part of a group relationship and it is not an open relationship. The term is commonly used by polyamorous people to describe relationships with only two people.

Resources

 * 1) https://pride-flags-for-cishets.tumblr.com/post/149195445851/monogamy-pride-flags