Because they are all Queer individuals.

From what we know, we have...Dorian who is gay, Sera who is a lesbian

Myself who is romancing sera and only has had interest in women in the game

and Iron Bull, who is pan.

WE ARE ONE BIG MOGAI FAMILY YAY

also two dating pairs. All our missions are double dates!

(if you don't romance Dorian or Iron Bull in a game, it's implied that they start a relationsihp of their own)