If your new SO got along with his childs mother
If his next of kin was his childs mother instead of another family member
If he and his ex (aka childs mom) tried to meet up once every couple weeks do something without any SO's allowed to come, like a sports game or museum. As a family mom, dad, child.
If he and his ex still see a MFT, not to work on the relationship, but to hash out problems instead of using the court system
If he and his ex have keys to each others house and know each others alarm codes
If his ex is beneficiary 50% next to 50% his child and he has no plans to change that even if he gets married, it will only change if he has another child.
is this stuff that would make you mad?