Newish girlfriend not invited to old friend's wedding

Started dating a girl 7 months ago, I'm in my 30s as is she. I'm Irish, she's south american living here a number of years.

I rarely see many of my friends these days. One of my oldest Irish friends of <10yrs is getting married in a couple of months. He's a friend who I've always regarded very highly and has always been good to me, and hopefully he feels similar about me, though as I said we don't see each other often at all lately. His fiancée I get along good with too, though I'd be around her even less.

Anyway the couple haven't yet met the girl I'm dating, though would be just about aware of her through my posts of her on instagram etc rather than any situation along the lines of me talking to them in person going "hey I'm in a relationship with _____ now", since I've not seen the couple in person nearly except once in those 6 months.

My invitation to their wedding just names me, the solo guest. I kind of forgot to expect this would be the case (my fault) for various reasons, and so I threw a very quick little text over to the groom to ask how feasible it is for me to bring my +1 to the wedding and he said "not very", as they're severely over-invited as is, but that she can attend all the post-meal post-sitdown parts no problem. The wedding is down the country and people are also staying all the next day so there's that part too she'd be there for no problem.

When she found out I might be going to the first parts of the wedding without her she freaked. Saying how rude is was for her to be excluded and she's never heard of this kind of thing in her life, saying if she's my girlfriend the 'of course' she must be invited to the same extent as I am. Which I understand, for the most part, but - they've never met her yet.

I explained this to her and she started hammering on what is a tired, sore subject for us - the fact that she feels like I don't include her in my life. What she means is that I didn't somehow introduce her to these people yet. But I live a very isolated life these days, I grew apart or distanced myself from a lot of my old friends in the last few years as I was going through the breakdown of a marriage that in the end I felt ashamed about. I've said to my gf many times that it makes me sad that I don't have the social life I used to where I would catch up with friends with any kind of frequency, she's well versed in this being the case for me and I've made clear I know it's not ideal and I would like to improve all that. But there's only so much I can do in the normal course of events - trying to force contrive meetups with friends has only ever made me feel worse when most of them flake, bail, send their apologies and it puts me feeling even more distant from them.

This guy (groom) is actually one of the only of <2 friends I have who in the past I felt was ever really "there" in all those times where it counted, where it meant a lot to me to have someone turn up to something. He's a really good egg, for me, I have a lot of respect for him and his fiancée and the last thing I would ever want is to be a demanding asshole toward them about this girlfriend invitation thing when I know how cutthroat and difficult it is trying to keep a guestlist within size and cost limits.

Having received the invitation and realised no +1 I already texted him to ask and he replied in the negative (but that she can come to the post-meal afters & day 2), she is seriously, SERIOUSLY raging at me for like being remotely accepting of the fact that this is sometimes the way weddings are in Ireland for people with limited amount of money. I don't think either of the couple have their dad anymore to be helping fund bigger and bigger guestlist.

My gf has an unfortunate frequent tendency toward taking small innocent details and feeling them as huge defamations or assaults on the entire value or legitimacy of our relationship (she got angry at me many times for not organising meeting my family sooner even though she herself was flakey about the details when it came time to actually come meet them). She'll then attack me and paint herself as a victim of being the neglected party and get extremely worked up and sometimes rude or lose her temper. If I say the wrong thing about my plans for a social event or travelling somewhere, she's usually with laser-accuracy there finding the insinuation that I obviously must not care as much as her about the relationship, and she is the one "giving more" all the time.

So my guard was up out of habit when she freaked about this invitation business. I explained it all to her and said I wasn't sure what else I can do, having already hinted at wanting +1, without starting to make an annoying nuisance of myself to the couple about it. I tried to explain it can be hard for everyone's other half to get invited sometimes to Irish weddings if they've not met the couple before.
She's utterly disgusted, blames me for NOT being as disgusted (even though I obviously sympathised and emphasised I would MUCH rather have her with me for the full wedding). She's told the whole situation to some of her friends in such a way that they obviously replied "oh that's unacceptable, my bf would never allow that" etc and came back to me with statements about that, which really, really annoyed me to think about.

So she's basically sworn off going to the thing at all, coming with lots of spiteful sounding comments like "you go by yourself, enjoy yourself, don't expect me to go to this or event XYZ or anything else from now on, I'm done trying so hard to be in your life, I'm done trying" etc
Obviously this precise situation hasn't come up before but when shoe's on the other foot I never react with so much negative feeling.
I'm just at the end of my patience and my wits now and don't know what to do. I plan to make another request to my friend the groom to see if I could somehow go without my meal and seat at that part of the day to allow her to be accommodated instead, it won't really bother me personally to do that but I know it sounds terrible to everyone else. I don't know. I've very little patience now at this point for her stance on it, she's holding it all against me.