Perhaps when I'm not at work I'll try to sit down and respond but I'm gonna drop the novelization here and we can just compare the intent between Sora's reunion with Kairi and his reunion with Riku.
I wonder how that reunion would look with Kh3 grafic because at least in the games itself Sora does not look joyful. Even in the FM version he barely smiles at all. A big difference to his big smile afterwards.
I will look forward to seeing how the KH3 novel will cover all of this.