Two layers: Position (who stands where) and Bond (who dances with whom). Left half = man, right half = woman. Same colour + number = original couple. Movement calls relocate couples but never change the bond – only a partner swap does.
Dot left = man at home · Dot right = woman at home (black = home, white = displaced) · red border = bond broken.
Mode “Move”: drag = couple swap with the neighbouring cell (the pairing runs across the whole floor). Mode “Swap partners”: drag swaps the women by the same 2-column / 2-row rule across the whole floor – the men stay put. Click + arrow keys also works.