"It is the symbolism, not the substance that matters."

If that's really what you believe, then I think I know the answer to why so many marriages go so horribly wrong.

Look, letters are often highly edited due to the small amount of space available. We don't know why LW's fiance is asking to do this. Maybe LW is a starving artist who wants to give his girl a ring but can't afford a nice one. Maybe they're thinking about starting a family together and want to buy a bigger home.

All I can see in that letter is a niggling insecurity that "she thinks her old life is better than this one," and that's something LW really HAS to get over if this relationship is going to work. She's divorced, she's willing to change the setting of the ring...she's making a compromise here. If he gets this worked up over a piece of metal and stone, what's next? He freaks out because she still sends Christmas cards to her former mother-in-law? She uses the blender she was given for her first marriage in THEIR kitchen? LW's fiance isn't tabula rasa, and it seems like she's being very practical about an expensive, extravagant expenditure.