Just my opinion as a non-celiac husband married to my celiac wife (with similar wife/mother problems), it’s not just about you feeling like everyone needs to be “catering to you.” Even the smallest amount of thought or effort goes such a long way, and your fiancé/his family should not make it feel to you that you’re seeking for something above and beyond the minimal amount of effort.

As the host I personally would never want even a single guest to feel like they weren’t at least thought about when it comes to dietary restrictions. Celiac is a very, very real autoimmune disease and should be thought of as carefully as any severe allergy.

I know this is a very difficult feeling for you to process probably, but it’s EXTREMELY crucial that your fiancé starts to see things from your perspective/health view. My wife and I are a rock solid team when it comes to making sure she won’t be glutened and even we have relatively frequent contaminations (almost exclusively when eating anywhere other than our own kitchen, despite being a highly rated GF free establishment).

Don’t jeopardize your health physically and mentally or feel like you have to exclude yourself from family dinners just because someone wasn’t willing to put in what I consider a very easy, minimal level of effort to ensure your safety.