Say a girl has a boyfriend who is a sailor, or is out of the country for six months. Could she see someone else, freely in the meantime, or should she wear a chastity belt?
And, anyway, should people be as faithful? I mean, we're not all swingers, but you do meet people you might never meet again in your iife and you might only have a few hours with them, even if you do have someone else. Maybe women could be just as impulsive as men in that circumstance?