Humm I knew a couple of MS who were cousins who swaped wives. The Uncle elders met out private reproof. The C.O. was furious and tried to remove all the elders. Neighboring hall.
A couple I times I heard of close couples who after drinking, dancing, on vacation- 2 individuals "hooked up". The "innocent mates" got angry and had "revenge sex". The situation leaked out and made the gossip rounds as "wife Swapping".