How? Lots of Canadians have been the US. And the cousin is talking, in context, about how the bride said she was going backpacking in South America for two months. I think it’s simply a way of saying she’s never been further south than the US, doesn’t speak Spanish or Portuguese and knows nothing about South America.
IMO, the article read as if the bride had never left the US.
But your interpretation could be correct, who knows?
With all the narcissists walking around today, I can see one behaving in this fashion.