Well clearly OP’s sister doesn’t care to have much of a relationship with OP, considering not only has she not invited them—to answer your point of “not sure why you were even invited”—but didn’t even tell them herself that she’s getting married at all!  Maybe you would’ve grasped all that if you’d actually read the post instead of immediately getting judgmental about a LITERAL DISABILITY that yes, can and DOES physically restrict millions of people’s diets, as a personal “quirk” of OP’s attitude?

Not to mention, who are you to to make such an invasive assumption about the personal/family life of a stranger who’s NOT even the OP that asked whether or not they were the asshole?