Tricky question: Can you refuse a groomsman's plus one?
For context, groomsman (also a family member) has been very on and off with girlfriend (-ish) for over a year. They've split something like 5 times. It's made FH sick to watch, but he's trying to remain positive, and doesn't want any advice to come off as trying to tell this groomsman what to do.
My only context with her has been family events, in which she consistently finds a way to offend everyone in the room. It's less of a difference of opinions kind of offense; the worst example has been openly calling the faith and traditions of someone in the room "made up." The first time we saw family after we got engaged, she went on-- at length-- about how marriage is a prison for women, how she'd never give her "power up to a man," how degrading marriage and motherhood could be, how terrifying and awful childbirth must be (we didn't bring up future children at any point). If there is something you enjoy, value, hold as dear, watch out-- she's better informed than you, will spend the night telling you, and will tell you why her opinion/value/choice is better. Most outings including her end in a monologue from her with everyone staring at the floor. She's been informed that she's making people feel like outsiders, and it's continued.
If this had been a one-off, I would've chalked it up to catching her on a bad night, but it's been every interaction for over a year. I cannot see the rest of our guests enjoying their evening with her there, and it's a small enough wedding (ballpark 50 people) that she wouldn't get lost in the crowd. I don't want to sacrifice the experience for our entire guest list for the feelings of one person, but I know that etiquette dictates she's supposed to get an invite, and FH feels bad. What do we do?