alisonjane33:

It's not true that she (I'm saying "she" somewhat arbitrarily to avoid "he/she" every time) said she didn't want to meet them ever.

I don't read it that way. She makes it clear they're not in regular contact any more, meaning this is sort of a reunion. These significant others are people she's likely never met before and probably won't be meeting anytime soon. Plus, she flat out says they're not important to her.

alisonjane33:

It's a perfectly normal, functional question that shows a perfectly normal grasp of the social issues involved.

To which the perfectly normal, functional answers are A) Cutting it from her 10 best friends down to 5 to accommade the significant others, B) Making it an open house sort of event where seating wouldn't be an issue, or C) Holding it at a restaurant. I'd think anybody who really was concerned with having a fun and successful gathering would come up with these without outside help. Instead, she's locked in on it being a sit-down dinner party at her too-small place that's going to be awkward for everybody.