That's what I love about Ann Leckie's Radch trilogy. Radchaai culture doesn't care about gender, everyone is a "she". All romance could technically be lesbian romance.
Also, subsequent novels introduce human civs outside the Radch with complex gender systems and relationships, and Radchaai are seen as arrogant pricks who keep misgendering people. Hilarity ensues.
Also very good modern space opera, highly recommend.