I have about 10yr of exposure to friend groups with nonmonogamous lifestyles, and it’s by a long shot the women who are having multiple regular partners and the men who have an occasional fling. And I find just as many women as men choose to adopt that kind of lifestyle. Obviously there are exceptions, but this has been an extremely stable general trend I’ve observed. This is of course caveated by having a small sample size.
That said I think the trope that women only want one sexual partner while men want many is—in my experience—nothing more than that: an outdated, overused trope.
I’d love to see some actual numbers. But what numbers I have seen seem to be easily skewed by the reality that it’s more socially acceptable for men to have more partners (though that stigma is quickly changing).