From experience the first thing that needs to stop is the questions. Do not ask the child anything about the other parent or what goes on at the other parent’s home. If they volunteer information that is different, but you don’t have to react. If he tells his dad that he wants to live with him, the reply should be that that is not his decision. They have custody arrangement or agreement and until he is a little older he does not need to worry with that. Take the pressure of him making a decision like that off of him.
If the ex and your spouse can discuss things, then sit down and discuss that what goes on at one house is no business of the other parent unless the child is in danger. It sounds as though the child is manipulating each parent and though he may not be doing it on purpose, that is what he’s doing. Do not be mistaken. ALL children want their parents to be together. Yes, he wants to make whichever parent he is with happy. He thinks that if he talks badly about the other parent (or stepparent) that the parent he is with will be happy. He thinks that his parents want him to choose one over the other and children should never be forced to choose. He needs to know that it’s not his choice.
If you and your spouse quit reacting to what he tells you, unless it’s something major, and the other parent quits reacting to things, eventually he will understand that there is no need to tell things. And there really is no reason for him to discuss what goes on at each parent’s home.
If your spouse has not allowed him to do something or has allowed something, then that should need no explaination. That is his parent and there are going to be different rules at each home. As parents, your job is to make sure he is fed, clothed, gets to school, and is sheltered. Everything else is circumstancial. The other parent has the same responsibility. If there is something interferring with those fundamentals then there is a problem, otherwise it’s only making a difficult situation more complicated.
I’ve gone through and am going through similar situations. The child learns how to react by watching the parents (and stepparents). My oldest stepson is a master at taking the focus off of himself. If he hasn’t finished his math homework, all of a sudden he’s got serious questions about a work project his dad has…changes the subject anytime he sees it going towards something that he needs to do or correct. He’s 13 and the youngest is 10…we want them to be happy but there’s little that we can do if they refusing to allow themselves to be children.
For all your sakes, it will be easier if the adults take a little control over the situation.