Patriarchal polygynous culture v. matriarchal polyandrous culture.
The central 'bargain' of a marriage is (a) the man will protect and provide for the woman so she can nest and have children, provided that (b) the woman will have only his children (so, sex with only him). Everything else is companionship, or entertainment, or ego needs, or whatever, but in contract terms, provision-for-faithfulness is the foundation on which everything else is built.
With that in mind....
The world is violently against the idea that a man would provide for more than one woman, all of whom are sexually faithful to him alone and bear only his children.
The world is perfectly okay with the idea that a woman would have sex with and children with as many men as she pleases, racking up additional child support from each additional sucker (oops, I mean each additional man).
The man is not allowed to expand the basic bargain beyond one woman (at a time). The woman is allowed to expand the basic bargain as much as she pleases. The man is not allowed to build a bigger family based on loving relationships at the expense of the accumulation of material wealth. The woman is allowed to build as big an income stream as she can get away with, at the expense of loving long-term relationships and the mental and emotional health of all affected.
I know several women drawing child support from three or four guys, while going through husbands and boyfriends without shame or even any self-awareness that what they're doing might be counter-productive (except for blaming all that on the men's failure to act the way she wants them to act...).
Matriarchal polyandrous culture: One woman, many providers.