A mother obsessed with her son is a narcissistic mother. This is the kind of mother who does not give her son space to grow on his own.
Narcissism is the pursuit of attention and gratification through admiration for achievements, beauty, charisma and other successes. When growing up, boys tend to do whatever their mothers ask them to do just to please them. When this persists, it creates a behavior where the boy cannot appreciate his own deeds but only strives to please his mother. As a result, he ends up tied to his narcissistic mother, who believes everything is all about her. In such situations, the boy does not get enough space to do whatever he feels is right for him.