I'd like to make a thoughtful comment, but I'm struggling to get past the phrase 'age-appropriate'. As someone who has never been 'appropriate' to their chronological age in any respect, it always comes across as reductive, patronising and ultimately dehumanising. It seems to me to be the product of a worldview which sees children not as distinctive individuals with unique preferences and aptitudes, but as mere larva…
She lets the guy get a broader perspective, by reducing her own importance in his life, by letting him discover a taste of a life without her, and yet you, and others, manage to interpret that as a sign of narcissism. I don't understand that one bit. It could as well have played out in a completely different way, where the guy liked his newfound freedom enough to go through with the separation. The fact that he stayed is a pretty strong signal that she was right and that it wasn't about her, as she guessed. A narcissist couldn't possibly guess that something wasn't about her.
Your story boils down to 'guy finally has the guts to tell her how it stands, because he is sick of her emotional blackmail, but he's actually a pussy, because a new bit of emotional manipulation is enough to make him reconsider'. That really doesn't sound very convincing.