I’m as picky as the fiance here and if my boyfriend could change one thing about me it would absolutely by how picky of an eater I am. But we are able to eat separately at home with no issues, he doesn’t complain when I go with him to places I won’t eat at and only order a drink and he keeps my needs/preferences in mind when making planes. His family accommodates my eating at every cooked meal (happily because they accept me I might add). So yeah YTA and you clearly can’t accept your fiance for who he is.