In this case, the selection cannot be repeated, so every time we select someone, the other people's chance of being selected increases.
There are 6 couples, which means there are 12 people. We have a 1 in 12 chance of choosing a certain person, the person we pick is named Dan. Then there are 11 people, we now have a 1 in 11 chance of picking Dan's partner. The probability increased because Dan cannot be picked again. 12 x 11 is 132.
