[analyst74]

It's not just inequality between males, but also the wellness of poor people.

If people worry less about starvation, they will put less emphasis on potential partner's financial status.

[s_dev]

That doesn't explain polygamy in the richer parts of the Middle East where it's far more common than Western Europe. Starvation or even significant malnourishment beyond ones own poor choices aren't common. Relative economic inequality is common though to both places.