Sorry I don’t mean to invalidate. I understand not wanting to go somewhere. Don’t even need a reason not wanting! It’s ok if you don’t go. I was just trying to give a positive spin to it. There are reasons not to go (discomfort and just not wanting) and reasons to go (you will have to have these people in your life and it’s important for your fiancée). If you go you might get to know few of them and then it will be easier in the future as you will have to see these people. Or maybe food will be good. Or something else might be fun. Just weigh pros and cons and see which ones wins

But you are totally free not to go. Send a gift and say you are sick.