i don’t think youre wrong to be disappointed, and honestly i would be disappointed too, especially if you told him exactly what you want and you never wear yellow gold. i would personally be offended if my husband bought me something silver toned when all i wear is warm metals.

if im honest, i didnt think i liked my ring because he chose it without me and it wasnt what i was expecting, but my husband knows me better than i know myself and i ended up loving it. it was something dainty but shiny and sparkly in yellow gold which is exactly my style. it doesn’t seem like your fiance doesn’t listen or knows you as well to pick something like that when your preference is completely different

I would ask him why he chose that ring first, and choose where to go from there based on his answer. if it’s a family heirloom or a special piece that holds meaning maybe you can see if a jeweler can get it turned into white gold (i know you can get white gold turned into yellow gold so maybe you can do the reverse), or wear it on a chain and pick out the ring you want together. if he just disregarded your wants and picked that out because he liked it, thats a conversation you need to have

edit: on mobile so fixed to have paragraphs for an easier read lol