I think this is all over rated. Who the hell cares if the new girlfriend meets the mother of the kids. What is meeting them going to prove and tell the other? Okay, the girlfriend has black hair, wears Lulu Lemon and doesn't file her nails right... the mother is a teeny bit overweight, gets professional highlights and her shoes are cheap or expensive...that is what these little meetings really are about - they give ammunition. Let the women work it out themselves IF at all... it is their choice. They opted into a relationship with their partner and his children, they didn't opt into it with their ex.
Now some of us can have a relationship with the ex. I do - she curses at me regularly lol. I'd like to think she is drunk as heck when she sends me her rants, but no, she is stone cold sober I'm told...
I've even offered to meet with her. She prefers to hide behind her emails. Fine. I don't respond to her emails for the most part because they are useless and normally about my private life and I don't want to invite her in. I have set boundaries although several years later she still refuses to abide or even acknowledge them. So be it. I still ignore them.
So, the moral of my story is, I do believe this is about control. I am a mother. I am a stepmother. If I want to meet someone I will extend that invitation to that person myself. The only reason I extended an invite to my partner's ex is that she continuously emailed me many, many, many times a day and a week. I figured she must want a relationship with me otherwise she wouldn't be doing this. She then told me that she had to see that her ex had changed before she would ever meet with me. So here we are several years later and we have spoken only twice ever despite a hundred times or more having had the opportunity to speak. So you see, at least in my case, this IS about control. She wasn't really interested in talking to me, or getting to know me (although she asked her ex many times to meet me). This was about controlling my and my partner's time through emails, and about peaking into our private lives.