I just got an RSVP back for my wedding from my Aunt, and she tacked on an extra guest- the girlfriend of my cousin- who definitely wasn't invited. It's very possible my cousin is living with this girl- I don't keep in touch with them at all and haven't seen him since I was a really little kid. Is it my fault for not knowing he has someone, and the bad etiquette is on my end, or is it super rude of her to just add a guest without asking me? What should I do?