AIBU to think people are allowed to be disappointed about cancelled weddings, not being able to go on the holiday they were looking forward to, birthday plans being cancelled, not liking the house they live in, etc.
I think you have two choices in response, either 'yes, you must have been looking forward to that, what a shame' or 'for goodness sake, there's a global pandemic, don't you have anything better to worry about?', and which one you choose says more about you than anything.
AIBU to think there's always been something awful in the world that you could point to and say 'how can you be upset about when that is going on?!'
AIBU to think that unless its excessive and prolonged, let people be upset about things?