As soon as there are larger autonomous cars, it is not unlikely that whores will discover this new possibility and offer a rolling whorehouse, so to speak. Or couples have fun while driving and have sex in the car while they are being driven from A to B.
When we talk about a triangular relationship, this usually refers to the constellation in which a man has two wives. In addition to having a lover or affair with a steady partner, the classic triangular relationship is to have one. It occurs millions of times. The reverse case is not uncommon either.