Welcome to MB.
I moved in with my gf one year ago, and we have been arguing for the same reasons. I complain about her not having the right boundaries in place. I respect they have to co-parent, but what I don’t want in my life is dealing with him. For example, I asked her that when he has to come and pick his daughter up once a week, he should stay at the door and not come in. I asked her to limit their contact to their daughters matters, but I never been listened to. She told me that if I didn’t want him stepping in, she would have done 2 trips at his place, one to bring her daughter and one to pick her up.
I wasn’t happy at all with this decision but she kept going for a year.
Now, because I feel I have not been listened to, I am moving out.
I was wondering if the policy of joint agreement could work in my situation, where there is a 3rd and 4th person involved.
Thank you.
For the policy of joint agreement to work, both spouses have to use it. There are situations where one spouse tries using parts of it single-handedly because the other refuses to work co-operatively on the marriage, but a one-sided operation is not "joint" agreement.
When a couple is considering marriage, a good test of whether to go forward with the marriage is the attitudes of each to POJA. (You didn't say you were considering marriage, but you were living together.) It is unlikely that they even know about POJA, but they should be able to focus on whether the other person is willing to take their views into account in all decision-making, and whether they are willing to give up behaviours, including those we might consider personal choices (like specific sports, drinking, gaming, pornography), that make one person unhappy or feel excluded. If one partner insists on their right to keep the friends they already have, or, as in your case, to maintain the relationship they have with their ex, they are refusing to do POJA and the relationship will be unhappy, and might even end, as yours is doing.
You see, for the purposes of POJA, it doesn't matter whether there is an ex involved, or children from a former relationship. That does not make it a situation "where there is a 3rd and 4th person involved"; there are only 2 people involved in a conventional marriage/living together - or there should be, and could be, if the person with the ex were willing to put the current spouse/partner first and only.
From what you've described, your girlfriend was unwilling to put your feelings and desires first and only. If she had been willing to do that, she would have taken into account how you feel about her ex, and kept him out of your relationship and out of your home. She would have put "the right boundaries in place" as you put it. She would have talked to him ONLY about arrangements for her daughter - and how much is there to talk about, really, once pick-ups and drop offs and holidays are established? Parents' evenings can be done separately - schools are used to this. He could attend school events without any real interaction. Christmas and New Year are swapped each year (or whatever they previously agreed). There are occasional days of illness, and even fewer of emergency. What is there to talk about? Many parents make arrangements via an online calendar, to avoid direct conversations that often end in conflict.
There is no such relationship in which "there is a 3rd and 4th person involved". Her ex and her child are not part of the relationship between you and her. If she had been willing to use POJA between you and her, your relationship could have survived and thrived.
It is obvious that you are familiar with Dr Harley's work; did you ever try to interest her in the concepts? Did she reject what they offered? (It would seem so, given what you have written.) I think it's one thing for a person not to know about POJA - let's face it, it's a pretty odd, and rare, concept - but an entirely different one for someone to be introduced to it and to reject it. If she rejected it, she was pretty much telling you that your relationship was not a priority in her life, and that her own wants and desires come first. If that was what she projected, then there was never any hope for your relationship and you are doing the right thing to leave. It's not that POJA could not work, but the lack of its use that is causing the break-up.