The cravat is a new renewal of an old style. Swallow tail coats were once pretty common for day wear, and they were worn with a cravat type tie. And spats, but I won't open that can of worms here.

True, you can wear what you want. A tank top with a kilt and PC is not illegal, just tacky. But some folks like tacky.

Taditional, at least in my tradition, would be a bow tie with a PC--after 5:00! But these days you see tuxes and tails at all hours, I suspect because people equate "dressing up" with tuxes and tails; they just don't know the difference between a day coat and tails.

Wearing a plain black long tie with a tux or argyl jacket would be the ticket for day wear--before 5:00.

Having said all that "Clothes Make the Man" crap, I would strongly advise that you talk to your intended and do as you are told. Life will be much better for you, and a tie is not something to fuss about. Leave that for going out with the boys or fishing.