Also consider, especially in old days, average man's life much shorter then woman's. For example: vikings: average man died at 23 average woman 45. War tend to do that. So many more women in prime then men. Slaves also tend to do so. I've known several bi-sexual women in 3-some type relationship...most seem happy....don't know all details of course.
I must have led a sheltered life, as I didn't know about a lot of this until recently.
I naively have always assumed that when women were cut off from men sexually from widowhood, etc., they didn't seek alternate sexual outlets, other than the self one perhaps.
Most women I have known would have to be in pretty dire straights to even consider such behavior, and I'm talking women who aren't particularly religious.