disguising the question "Who's the man in the relationshiP?"

At a party, two friends in a heterosexual relationship were dancing with each other to an upbeat song, and they noticed that the guy always grinds behind the girl. One of them asked my girlfriend and I (both of us are femme-presenting cis women) who dances in the back and who dances in the front when we go to parties. We were both very uncomfortable, because that's something we hadn't even thought about. It was clear what our friend was really asking was the heteronormative and outdated question of who the man in our relationship is...