Repost, with full text this time.
I (male, 41) have been with my OH (female, 37) for over 7 years now.
Early on she made it very clear she didn't want children and that was OK with me as I felt I was too old to be a good father, had taken a long time to get established in my career, and did not have much of a paternal instinct, but was very happy to be an uncle to my nephews/nieces. Otherwise we were on the same wavelength and got on well, and still do for the most part.
My sister on the other hand has young children who are adored by all the family, and this has become a massive source of tension in our relationship, getting worse year by year, to the point I'm not sure where things go.
When OH and I first got together it was not long prior to the pandemic and sister only had 1 child. Fast forward a few years and sister now has 2 more. DP and I had the experience of living together under very intense pandemic conditions while things were still pretty new for us. That seemed to go OK. Where things have gone wrong is the post-pandemic years where I've been trying to get her to engage more with my family. I'm talking maybe 3-4 events a year at most, think Christmastime and significant birthdays where immediate family + partners might be invited. Other smaller or ad-hoc get-togethers I would happily go to on my own, but it's important to me that we turn up together to "significant" family events and my family would probably ask concerned questions about the state of my relationship if I always turned up without her, as you can probably imagine.
Even this limited level of family engagement has been a struggle to put it mildly. At first it was at a fairly normal level of "slight unease around in-laws" which I assumed might be alleviated by better familiarity, but over the last couple of years in particular things have steadily got more and more tense to the point where I feel like I'm torn between my partner and my family.
DP's point of view seems to have shifted from "don't like children" to "actively despise them". Any time there is any kind of family event where children might be present I have to fight with her to get her to attend, and if she does attend then she spends the whole time sulking and pretty much refusing to speak to anyone. She is barely civil to my sister and brother in law, giving monosyllabic answers at best when they try to engage her in conversation, and looks through the children as though they do not even exist.
If I go without her she still finds a way to make passive-aggressive remarks about my family before and/or after the event, such as implying that I should just mail birthday presents rather than delivering them to my nephews/nieces in person (even though we live relatively close by and she knows I like seeing them) or making scoffing noises/rolling her eyes when I say I need to leave at X time to be there for such and such an event.
Even if we meet my parents without my nieces/nephews present she seems to try to find a way to start an argument, because she seems to resent my parents having a close relationship with their grandchildren. She also insinuates frequently that my parents somehow value me less than their grandchildren or that they give my sister more support than me - even though I've tried to explain repeatedly that this isn't the case and that it's quite normal for grandparents to dote on their grandchildren anyway.
This also gets echoed in my relationships with friends, most of whom now have children. She's still not met quite a few of my oldest friends and has turned down opportunities to meet them - if they have children she seems to pre-emptively write them off with sarcastic comments about how they've given up perfectly good careers, etc.
OH had an abusive childhood and I think a lot of this stems from the fact that she never knew "normal" family dynamics and never knew her own aunts/uncles/grandparents. She also seems to think that her mother (who was in an abusive marriage) ruined her own life and career by having children in the first place, and projects that onto other people who have children - hence frequent remarks at home about women "throwing away their lives", children in general being entitled, colleagues with children "skiving" when they are on holiday, and so on and so forth.
I think there is a lot of unresolved trauma here - almost as though she views herself as needing to avenge her mother - and a lot of fear or uncertainty on her part as to how to engage with family dynamics where children are involved. That said, she refuses to seek therapy - her view seems to be either that she knows better, or that nothing could help anyway. I try to support her as much as I can, and on a day to day basis it doesn't really factor into our interactions with one another as we have busy lives and don't have daily interactions with family. But it is getting to the point now where it is poisoning relations between me and my family whenever there's any sort of family event. We have had numerous arguments over the last few years where it feels like she is growing increasingly resentful of me wanting to have a relationship with my own nephews and nieces.
I don't want to split up with her. In private she is funny, clever, and incredibly supportive of me. But when it comes to meeting my family (or my friends) they are faced wtih indifference at best or even hostility, and that's beginning to spill into our private lives.
I'm at the end of my tether. After 7 years it feels like things should get easier, not more difficult. What do I do?