I’m sure this is very frustrating to you all. Thank you for writing.
Here are some thoughts that occurred to me as I read your letter: I don’t think the boy is “competing” with you. I think he is dealing with a number of developmental issues. He may not understand his parents’ divorce and may be afraid that his father will “divorce” him, just as he did the boy’s mother. He may think the change in his father’s behavior toward him (not spoiling him) is a sign that his father doesn’t love him any more. It may be that since there is tension between the boy and his mother, he clings to his father so, in his mind, his father can’t leave him too.
In addition, the boy is at an age when a kid becomes aware of sex and the reality that the adults in the house are being sexually intimate. The idea may be making him anxious. His solution is to do all he can to prevent you and his dad from being alone together.
Please don’t think about this as rational. It is quite unconscious. My take on the boy is that he is highly anxious about the changes in his family and his behaviors are a crude and unconscious way to try to get things back to his “normal”.
That’s my best guess about what may be going on. But an analysis doesn’t help you know what to do. Ideally, you and your boyfriend will seek out a family therapist who can delve further into what’s happening and who can give you practical suggestions about how to manage the situation.
I wish you well,