Stina2012:
Then we get an email a month later saying we are invited and to let her know which food item we will be serving for her at the buffet. Not bringing food luckily, just serving it to folks.

People are so damn self important these days. Yes, sure, there have been weddings that I thought we'd be invited to and we weren't, and sure, I might think "Well, darnit, why not?", but in the end - I don't care that much. I ultimately understand and respect that they had to make some choices and sacrifices.
I don't need an announcement TELLING me why I wasn't invited. If someone is truly concerned that I'll be upset, pick up the phone and call me!