My FH and I are planning an intimate destination-type wedding (under 40), we have most everyone's RSVP by now since it is a bit of a destination event. One close friend we invited we gave a plus one since he had been in a relationship for a few months, but they broke up a few months ago and now he's asking to bring his new girlfriend (new being about a week-long, and someone we haven't met or gotten to know). Everyone else that's invited we've known for 5-15 years, and we're both uncomfortable with the idea of bringing someone so new, especially since he's the type of boyfriend who will leave her during the events to hang out with our mutual friends.
We're also renting a large air bnb and when he was single we offered to let him stay there too, but there isn't room for her. He has a habit of planning trips or vacations in advance with girlfriends only to be broken up by the time the trip is actually happening.
How bad is it to revoke his plus one status (he wasn't even aware he had it before) since he's in a different relationship now and we don't know the guest?