It was something that I read from here:
https://www.vg247.com/2020/02/27/baldurs-gate-3-dungeons-and-dragons/Adam Smith, who is the senior writer for Larian Studios said this: "So, Lae'zel, she’s the Githyanki. And Githyanki don’t really do monogamy,” .... “So if you sleep with Lae'zel one night at camp, the next night you might well just find her sleeping with somebody else. And she’s going to be like, ‘oh, that was a bit of fun, wasn’t it? How are you doing?’" This exact statement is found towards the bottom of the page I linked, where Romances are talked about.
