Hi there,
With big and blended families, I think it's normal to be flexible when it comes to celebrating the holidays. I think of holidays as a season more than one specific day. With that spirit, it becomes easier to orchestrate celebrations with multiple family members given some flexibility in logistics--dinner at one place, presents and coffee cake the next morning at another place, take a kid out to dinner at a preferred restaurant the next night after picking them up at the airport, visiting grandma and taking her out to lunch the next day, etc. Adult children might need to split visits between parents and/or spouses/significant others. I think that's wonderful.
With the pwBPD in my life, I think she's not ready to celebrate holidays with extended family members, as she maintains her narrative that they are toxic. I think the real issue is that she feels inferior, and she doesn't want to be triggered by other people's happiness, nor by parents' attention focused on siblings. So what we have done in the past is to exchange presents just with her, sometime after the holiday--provided that she's still in the mood and decides to show up. If not, I'll save the presents for another time.
Yet I think the original poster's quandry reflects three underlying issues: first, the kids dislike the girlfriend and find her so toxic that they are unwilling to engage with her at all. Look, I understand that reaction in certain contexts--kids generally don't like to see their "real" mom displaced, and for their dad to dote on someone new. But given that the kids are adults now, and many years have passed, it's a pretty strong message that not a single child is willing to tolerate her presence for a few hours, even if it would make their dad happy. That to me indicates that the girlfriend's behavior is egregious.
The second issue I see is the girlfriend's misguided reaction to the upcoming wedding. I totally understand her desire for marriage--after dating for a long time, she might start insisting on commitment in the form of marriage, and if she doesn't hear a proposal soon, she might think she has been wasting her time. It's impossible not to dwell on marriage when other people around her are getting married. But she refuses to attend a family member's wedding because she can't stand it? Look, part of commitment (and marriage) is supporting one's partner, even through things one doesn't necessarily enjoy. To me it's a sign that your girlfriend isn't really willing to support you when you need it. Sure, she'll justify her decision on feeling traumatized, or slighted, or embarrassed, or "triggered," but the reality is she's not there for you when it counts in my opinion.
The third issue I see is your hesitation about marriage. Apparently you've been seeing your girlfriend (maybe on and off), for a long time now. Maybe you have what you consider to be a casual relationship, and that's OK--many couples want to keep things casual, provided they are on the same page. By now your girlfriend has shown you how she reacts to your family, and how she acts when things aren't necessarily about her, but you, your kids or others. The best indicator of how she will act in the future is how she's acted in the past. My opinion is that she will not change one bit once she gets a ring on her finger. If that gives you pause, then that's good information. Maybe for you, things are least bad exactly as they are right now.


