I don't think this is just a female relationship thing. I used to have a great, cooperative, friendly relationship with my kids' dad for several years after our divorce in 2000. Or so I was led to believe. I had the kids stay with him for a few months while I relocated to his area for career reasons. When I had difficulty with locating a job that replaced the income I had in the previous city, he continued to "support me" in agreeing to extend the stay of the children. I agreed, because it was best for the kids.
Little did I know, he was plotting with his old divorce lawyer to use this as leverage to gain full custody. He had to tell some amazing lies in court, and my son was pretty brainwashed and agreed to stay with his father by this point. Since he was old enough to make his choice, and not wanting to tear down the man as a parent the way I had been, I relented and took the higher road, than forcing my son to testify against his own father. My daughter had already left months earlier and was living with me after I discovered that the stepmom was trashing me as a parent in front of my children, blaming me for her personality differences with my son. It was ironic, considering that although I disagreed with some of her parent choices with their child, I always defended her openly, insisted on proper respect and authority for her, and advocated for her right to parent her own child differently from mine. My daughter confronted her, packed, and called me to come get her. The light bulb came on for her.
I know he wanted to be near the kids (daughter was not his biological child)and I wanted that for him and them. I think it was incredibly enlightened for me to move 250 miles, be willing to live within walking distance of his home and their school, and have an open access agreement for the kids. That was not enough for him, I guess.
After the court hearing and the custody change, I rarely see my son...and some of this was passive aggressive action on behalf of the stepmom interfering with visitation, and some of it was just the boy being a teenager and wanting to do school stuff and be with friends instead.
In public, my ex is still friendly, and I am cooperative with him in regard to the children's needs and school activities. I am strictly polite with his wife, but I do not talk to her or him anymore. They are "frenemies"...I cannot trust the stepmom to respect me. She manipulated and pushed to try and get rid of my influence in my son's life so she could get her way. I gave her the whole, dirty, messy, inconvenient job...I am the one who now just sits in the bleacher, cheers him on, takes him places, and gets to love on him. I don't have to discipline much anymore. I miss his presence, wish I could be there more, but it is good when we are together...this too shall pass and hopefully will see more of him on his terms once he has his license to drive.
My advice to other women: you divorced your ex for a reason...be careful trusting them with too much information or asking for too much help. I allowed him to see my vulnerability, and if he had truly been my friend, he would never have taken advantage of that trust and confidence; he would have worked with me to share in the experience of raising our children. Is your ex spouse your "friend" even though you split on good terms...or are they really a "frenemy" just looking for your moment of weakness? It is a fair question to ask.