As we shall see, when females mate with more than one male, War capers nimbly through the boudoirs, imps of discord frolicking in his wake. - Olivia Judson

You’ve just got a case of SINBAD: Single Income, No Babe, Absolutely Desperate.

Evolution does not obey human notions of morality, nor is human morality a reflection of some natural law. The deadly sins would be different if they mirrored evolutionary no-no’s. Lust, for one, would be deemed a virtue; chastity would be deplored.

If a proclivity for promiscuity is genetic, then yes, promiscuous behavior will become more common if loose females tend to have more children than their monogamous peers. That’s how natural selection works.