Nothing in my comment is saying that buying an expensive ring will save a marriage.

I'm only saying that if your marriage lasts for 10 years, which about 66% of them do, it's weird to complain about the cost of a ring when there will be very many more expensive and equally bullshit things to spend or not spend on.

That paper doesn't attempt to make a causal link. It's possible that being broke during the courtship process (when the ring is purchased) is what leads to a lasting marriage. I also can't find any discussion of the cost of the ring to the cost that could have been afforded. Is there a comparable outcome from someone who could easily afford a $10k ring but instead spends $1k vs someone who can only barely afford the $1k ring in the first place?

Cool, if someone's prospective wife doesn't want a ring they can spend the money on whatever they want.

Here, though, GP makes it sound like his SO wants a diamond ring.

A US marriage is phenomenally expensive. If you want to send 50c a day to Africa, and you can't afford it, it's probably better to cut back on dressed chairs at the wedding than to tell your future wife who wants a ring that she's not going to get one.