I'll try and be brief;
We're getting married this week, and a friend has just messaged to cancel, on the basis that we didn't invite someone else and she doesn't agree with it.
Scenario is 8 girls in one friendship group. 7 of us used to spend a lot of time together when we were all single, the 8th (let's call her C) would join occasionally. Since the pandemic we're all in relationships and 2 have moved away. We've drifted apart some but still speak / meet up semi-regularly.
I've never at any point met up with or even spoken to C outside of the group scenario. We're not friends in our own right.
When it came to planning our wedding we wanted to keep it small and intimate. We invited the other girls, plus their partners since we know them. We didn't invite C in