One of my fiances longtime friends has an SO neither of us care to hang around but tolerate it more so because well we have to. That being said we want to avoid her coming to the wedding but are unsure how to explain it. Just gets loud, talks over you, me me me and ends up just sloppy. There's a bit more to the story history wise but I'm just doing the much shortened version. We were suggested that instead of allowing SO's we just invite the employees as a group ( fiance owns a business and friend is an employee ) as none of the others employed have SO's. He also doesn't want to cause tension between us and them but we also don't want the drama. I just don't want the potential of or the headache of having to maybe deescalate a situation or make family/friends deal with it.
Re: Avoiding a SO
Honestly you probably won't even know she's there. The day will most likely be a whirlwind and you'll be talking with and interacting with so many people.
There's a few dynamics at play because your FI is also the employer that can get sticky for him rather quickly but also etiquette is they're invited even if they choose not to attend with their SO. "Annoying personality" is not a reason to exclude a SO!