Most dance are unisex even most of the female and male specific dances. as for a dance that is with 3 people, unfortunately this is not a normal set up but most Huds do allow up to 30 people to join in doing the same moves.
if you are good at remembering the dance steps and routines it is possible to do some dances where you face each other and weave in and out of each other, this takes some practice but is possible.
I may only be new to SL but to dancing well that’s something I have done in RL for over 30 years now, so I kind of find the breaking of steps and joining of styles to be easy, but with practice everyone can do the same and its easy
Unfortunately the huds are not all that for couple dances as most require you to drop posse balls and as we all know no hardly any club if any at all allow you to rez items which is needed for use of the pose balls.
you could if you want to use a dual hud set up so that 1 or 2 are on one hud and the other/s are on another and you blend the steps into a routine, but this can be a very hard thing to do if you are not familiar with dance routines.
Hope this helps, if you need any advice I am more than willing to help out in game if you feel like it.