Someone help me on this.

Is there any justifiable reason why the father has to stay the night..actually stay the weekend by the mother of his child‘s house? Their child is seven years old. My now boyfriend of 10 months and I live together. I met the child and he adores me and I adore him. My boyfriend told the mom about me and she refuses to meet me or let her child around me. She’s threatening to keep the son away if he doesn’t move out & get his own apartment again or come stay weekends with her. Shit doesn’t make sense to me. He says he doesn’t want to take her to court but she’s making it hard for him. Smh