TLDR? The cliff notes: No cousins are being given a plus one unless they're married, but a cousin's new boyfriend recently made a comment indicating he thinks he is invited to our wedding.
Looking for some +1 guidance!
When we first got engaged, my partner and I decided to set a blanket rule that you had to be engaged, married, or living together to get a plus one. Part of that rule was based on the fact that collectively we have quite a few cousins in their mid- to late 20's who have boyfriends and girlfriends. We don't have the space to invite them all, and we certainly don't want to be in the business of determining whose relationship is more or less 'meaningful.' We felt this was a fair and easy rule.
Over the winter holidays, I met my cousin's new boyfriend during my extended family's Christmas celebration. While she has been dating him for about a year, she did not tell the the family about him until quite recently. As such, we certainly didn't consider him while building our guest list. Although I barely interacted with him, when he left and said goodbye he added: "see you in June, or July, or whenever it is!'. Our wedding is in June, and my cousin's boyfriend clearly believes he is invited. I was take-aback by the assumption, as I would certainly never tell a couple I assumed I was invited to their wedding! I felt like both the delivery and the assumption were quite rude.
We are about to send out our invitations, and he is still not invited. However, I am worried about how my cousin will react when she realizes he isn't on the list. Should I just wait and see if it's a non-issue (I don't know if my cousin herself thinks he is invited)? Should I call her when we mail the invitations to let her know the news? How should I reply if she requests to bring him regardless? This has been weighing on my mind a lot.