[atleastoptimal]

I understand the point your making with respect to most things. Wife wants 1.3x price carpet instead of x price carpet because it looks better. They discuss and compromise. Husband wants to go to 2y price vacation instead of y price, they compromise on 1.5y price. Bride wants z+50 people at wedding and groom wants z, etc. so on. The synthesis of love languages, consumer culture, the psychological musings of commitment, devotion, the pleasures of our immortality projects in monogamy, etc. is deeply ingrained into the human experience. It's a part of why we live, do things, work our psyches into powerful frenzies on the esteem and cares of others. I get that. It's wonderful, it's beautiful.

However, I personally think the "rings must have a very expensive diamond" thing to be very silly. I know that it may be subjectively very important to the potential recipient, but that it seems to sometimes really be so inflexible feels murky in the "what normally tacit power dynamic in this relationship is this revealing?" sort of way. The only significant tangible difference between the diamond and moissanite is the mental totem: "It is a diamond, he bought a diamond for me. He wanted to buy something else but I wanted this and he got it". Which is a problem when it comes to that: that the recipient cannot budge on something so arbitrary. It feels more like the whispers of the DeBeers cultural brainwashing: "You don't deserve to have her if the sacrifice you made to purchase this wasn't big enough"

If a woman gets X amount of utility from a diamond ring over an alternative, how would it be invalid if I said I got -X utility from having to purchase it?

This is one of those hard to beat arguments where I know I'm not facing a purely rational point of view. I understand it, that's why I added the first paragraph of this response. It's one of those issues where I feel I'd need to have a Christopher Hitchens level of rhetorical skill to make any headway in my favor.