One of my fiance's best friends (Carl) started dating a girl who was in their extended circle of friends. They all grew up together but were not necessarily friends growing up. When I met her I disliked her so strongly that I said half-jokingly "She's not going to be invited to the wedding just so you know."
After about two years of misunderstanding, we finally found our footing and she turned out to be a great girl. She moved in with Carl, helped him through his parents' deaths, lived with him for 5 years.Because they live in another continent, I saw her maybe once a year.
We sent out the save the dates, and Carl immediately called us to tell us that they had been broken up for weeks, which shocked us, since they had just bought a house together and put up a business. Anyway, it was pretty amicable and she is still friends with him and all our friends who live where they are. They don't hang out, but they do run into each other and it's ok.
So now the dilemma is, this girl was only invited because she was with Carl. She would never have been invited as part of the "peripheral" group. I sent a save the date addressed to the both of them. It isn't important to either of us that she be there, though it wouldn't bother us either if she were. We have kept a very small guest list, and uninviting her (or not following through on the save the date) would free up an invite for someone much closer to us. Should I invite her anyway?