It is hard for the adult couple to have fun together with their partner when one of them has cheated on them. While most of the couples enjoy having sex with each other, there are some that feel that it is better not to have fun with their partners when there is something like infidelity. This is where the threesome comes in. The threesome or foursome is when more than one person has a threesome or foursome with their partners. Most adult couples to have fun with their partners and this is why most couples cheat sometimes but having threesome or foursome is way better than having a one night stand..