I don't know how the one man/one women rule started but I know how it got into Christianity. The earliest converts were Roman women and, in the first couple centuries of Christianity, the church had the gender breakdown of a bridge club. Sure, the men were in charge but they had to address the needs of the flock. Women, probably because of maternity, are less likely to want multiple mates. It is every man's fantacy that women are as constantly horny as men but, alas, it ain't so.
This gender generalization seems to hold true, even, among gay men and women. There may be female equivilants to tea rooms, glory holes and the baths but I haven't heard of them.

                     Mike