I have nc'd for this.
I have been invited to a wedding of someone I was friends with growing up and we reconnected over the last few years as she is now also my sil's sister.
I accepted and was looking forward to going.
Fast forward a few weeks and my DB and SIL have split (totally his fault, and its now getting very complicated - that would be a whole other discussion).
I am now a bit wary of going, as I don't want to make anything awkward for her or her family (it would be, I cant say too much as I don't want to out myself) on her wedding day, so I know the right thing to do would be to speak to her about it and pull out (there are still a few months to go and the situation might change I suppose but I am conscious of how much notice she would need).