Boys, I’m afraid the way to a woman’s bed is often through her stomach. - Olivia Judson

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.

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.