It’s all comes down to money and assets. The way it works in the US is, broadly, they get half of your shit unless you signed a prenup.

That is a weird way of putting it. In a marriage, it is both of your stuff, which is why it is not so unreasonable to divide it equally. Obviously if you have only been married for a day then this is not so just, but I think for this reason that in some localities not everything you own immediately transitions to being co-owned.

This is ironically a callback to old school patriarchal structures where a woman divorcing her husband often did not have any marketable skill sets because they were housewives. The courts saw fit to have the husband continue providing for them until they are self supporting- conceptually.

That is alimony, which is a separate thing that only applies I’m this specific case.