B: How so?

A: When I got started, couples were nearly always male/female jet/ruby.

B: But doesn't that men that men would be leading all the time? A whole evening of men telling women what to do?

A: Pretty much.

B: That's pretty sexist. I'm glad we don't have that anymore! How did we get from there to here?

A: Well, first you started to see more same gender couples. Some combination of people becoming more accepting, people wanting to dance with friends and good dancers regardless of gender, and people wanting to get to dance both roles. Over time you got more and more of a mix, where it became first acceptable and then common for people to dance with whoever and in whichever role regardless of their gender.

B: And that's where we are today, right?

A: It's more complicated than that. Yes, at that point you could dance with anyone, but the social dynamics hadn't settled yet (as much as they ever really settle). So dancing mostly with men might indicate that you were more attracted to men, but it might also just mean that you liked following and there were more men who knew how to lead (see: sexist history of leading above). But then, over time, as we settled into this configuration, new social implications came up. Like, how often do you dance with someone of the same gender now?

B: Most of the time, really.

A: And when do you dance with someone of the opposite gender?

B: Well, if I'm dating someone. Also, like, good friends and relatives and people.

A: Right. These days people dance most of the time in same gender couples, and what would you think if an opposite gender stranger asked you to dance?

B: I'd think they were hitting on me. I mean, we'd probably dance, if I thought they were cute, but it would be a pretty awkward way to start things.

A: With same gender dancing the default for partnering now, I do miss getting to run through a whole dance with someone of the opposite gender in a not-dating sort of way. You could be flirty or not, and you could smoothly move up the flirtyness ladder if both of you wanted to climb it, or just have platonic fun. Now you need to do all of that in the context of quick neighbor interactions. It's actually kind of what my grandparents would say about dating. Back when it was standard to go out for the evening on dates with lots of different people before deciding to go steady with someone you had a lot more time to explore how your interactions worked with each of them, but as "going steady" became "dating" and the expectation switched to you only going out with one person at a time, they say we lost that. That was all before my time, though.

B: I don't know. I like the way we dance now. Asking someone of the opposite gender to dance is really hard. You're really putting yourself out there, and the fear of rejection is, in my experience, justified. It's just so much more comfortable, at least as a straight person, to spend the whole evening asking people to dance in a way where no one will read any romantic intent into the question.

A: But back when opposite gender partnering was normal asking someone to dance wasn't asking them if they wanted to date you or anything, it was just a casual thing, like "I think we'd have fun dancing together, shall we?" I mean, of course sometimes people were asking people who they were attracted to, but not everyone is straight so you still have that now. But because it was common to have casual opposite gender partnering it was just a so much weaker signal of romantic intent that people could be pretty relaxed about it.

B: I don't know, I think I'd have too much trouble asking anyone to dance back then. That just sounds too stressful to be fun.

(The main thing that makes me think this wouldn't happen is that, as A and B say, lots of people aren't straight. Still, there are enough people who are primarily interested in opposite gender people that I could still see things going this way.)