So this definitely works for hunter gatherers and that’s definitely how humans are architected, I agree.

However, if I think through what this process would look like under modern living arrangements, what would happen? Intensified serial polygamy with a massive increase in single motherhood? Full on polygamy?

Our social structures aren’t really set up to handle that. It seems like it would be so bad for society that I wouldn’t really say men are “disposable” under the current arrangement. More like they are the roof and women are the foundation, maybe.

It’s better to lose your roof than your foundation, sure, but losing your roof is still really bad. It does not really compare to, say, throwing out a paper coffee cup.