I can HEAR him telling Emma/Henry that there’s no greater pain than regret, and I can hear them answering “Try abandonment”
He just needs to say it to Henry. Emma’s gonna remember everything pretty quickly, including that Neal didn’t just abandon her without reason, but Henry won’t, and having the regret/abandonment conversation between Neal and Henry is so agonising and perfect as a parallel scene to the Neal/Rumple conversation, that it HAS to happen.