I can't fathom how she thinks that is appropriate behaviour! Weddings aren't an open free-for-all!
Believe it or not, I know I was amazed when I heard it, but there are people who think weddings are open free-for-alls. DH & I know a musician who is socially oblivious; Not just etiquettely challenged, but downright rude at times. Let's call him RG for "Rude Guy."
RG found a woman who agreed to marry him, which was the first surprise. They set a date & he made no secret of the time & place, speaking freely and frequently about their plans to marry & celebrate afterwards. We did not receive an invitation, so, of course, we did not attend. We spoke with some other acquaintances and they all said they did not receive invitations either. Many of us felt a bit put out since RG spoke about the wedding so much. It felt like he was rubbing our noses in his fancy wedding to which we were not invited.
After the wedding, several people asked RG how the wedding went, and he asked why none of his friends showed up. We all looked at him blankly, then glanced at each other, then said, "Because we didn't receive invitations." RG says, "Who does invitations anymore? I told everyone where and when. Why didn't anyone come?"
RG's fiance sent invitations to her family & friends, so it was a very lopsided celebration.