Given are three married couples.
So, let us assume there are 3 men and 3 women
They are sitting in a row of 6 empty seats
There is a definite order constraint that each woman will sit left to her husband. The first woman gets 3 options to choose from 3 available seats. The second woman has two options left as already one seat is filled by the first woman. The last woman has one option left. So, it is
So, number of ways is 3! = = 6 ways.