Ok, here's a little backstory:
Our guest list has been finalized for quite some time now, and save the dates were sent out six months ago. We have budgeted for and can accomodate every single person on the guest list if they choose to come, but if they do we will be at exactly 100% occupancy for the venue.
Here's the problem:
We met this couple about 9 months ago and since we sent out the save the dates we have become really good friends with them. We knew we wouldn't be able to invite them so we tried to avoid the wedding conversation as much as possible but of course it's been brought up. They ask how the planning is going and they talk about their future wedding plans (not officially engaged but close) and have even told us we will be invited.
We try to avoid the conversation as much as possible (we don't bring it up, we keep answers short before changing the subject) but effective bean dipping is just much easier in theory than in practice (my FI is especially bad at it, though he tries) and even more so when there's wine involved (there usually is). So the wedding has been discussed a bit more than I'm comfortable with with people who aren't invited.
Anyway, our invites went out this week and I feel so terrible because I know they're expecting to get one and they won't.
I know it's terrible etiquette to basically tell someone they aren't invited and why but I would really like to be able to give them an explanation rather than have them wait for an invitation they aren't getting before realizing they're the only ones in our friend group who isn't invited. They're too polite to ever ask if they're invited or bring it up themselves so basically I have no chance to explain unless I bring it up myself.
What would you do?