In our teens we had always been a close group of males and females so it seemed natural that in the early years we dated within the group. It was the case that each of the men had dated each of the girls; sometimes having sex on the first date, but always at a subsequent time. Never did we get involved in multiple partner or group sex even though at first there was a spare female.
Gradually individual preferences came to the fore and we all chose a partner; not in a deliberate way, it just happened. There was a couple of uncomfortable periods when two men wanted one girl or vice versa but they were soon resolved amicably.
