The double standard, at least in some sense, is good.

In my (twisted) view, males of the species are the performers and competitors, and females are the gate-keepers and selectors.

The reason is, in evoloutionary terms the womb is commoditized. It has a limited span over which it can function, and once there's a bun in the oven it can't be accessed for a year, and it degrades over time. So, the selection part of the mating process is really important: Only so many of us have the privilege.

So, at least from an evolutionary biology standpoint, the male who is selected repeatedly has at least that virtue of advancing the interest of the species. Apparently, he's the genetic winner and his seed deserves frequent purchase. But the converse isn't true of the female, in that sense. If the female's selection process is any swinging dick in the herd, she's not doing the species or the society any favors.

I think traditional marriage is supposed to be a buffer against the worst nature of both sexes, a covenant that allows partners to rely on one another amid a stable structure for rearing children. I think a monogamous marriage is the least sexist thing imaginable, given the nature of the sexes and our mutual interest in the species' flourishing.