In my cousin's defense, he has of the 3 women involved only his mother "loves all of his children." The wife and the ex each care only about their particular children.
He Is not bothered by his ex being present for holidays. He says that his marriage failed because of his selfishness and immaturity and that the ex is a good mother to his children.
I think that he has no problem with his mom inviting both women as it
her house and she has the same connections to both women. They are each the mother of her grandchildren.
I think that the 2 women view her as their children's grandmother and appreciate the love and involvement that she has with the kids I do not think that either of them want or need any more involvement with her than they currently have, and I do not get any sense that they are looking to change anything.
My cousin has a good relationship with, his mom and he understands that her approval of the women in his life is not required for him to have a happy life. She does not go into his house and she creates no friction in his,household.
Their situation ,at least on the surface, appears to be far less conflict laden than most of the relationships described on this site.
They all seem to have mastered the process of disengagement in a way that does not obstruct or interfere with their daily living. None of them seem to be longing for some lost or unrealized fantasy experiences. They seem to have created a process that works for them.
Isn't that what most people are seeking - a process that works for them?