Sex Before Marriage

Four unmarried couples meet the weekend before the marriage of one pairing. It starts with the hens having their sexy night out (which starts immediately they arrive) and the stags having theirs.

However an erotic bet sets up a highly sex charged weekend together which gets into a stimulating series of sex games. Is this changing the relationships between everyone? Are they getting sexually attracted to different partners, or are they just having very open sexual fun? Is it really love?