A story in the Foster thread of Part of the God joined together universe
Sylvia Foster followed her husband to Regina Canada and from there on anthropological field trips. She was her own person, though, and made her own life. Thursdays, 09/05 - 09/26
People can tumble into an isolated valley, but they can never leave. The original pair multiplies to make a thriving community. Then an infection robs all males of both virility and fertility. Community survival depends on a few men with normal sex drives who fall in. For some reason they all die during their sixth night (though they don't believe they will). Women have mixed feelings, but they make the most of the time the men have.
A young woman lets her boyfriend talk her into a scheme to roll drunk guys at the local clubs, but one night she gets much, much more than she ever expected when the mark turns the tables on them.