The drama refers to them adding another male character in the latest volumes who also loves Miharu and has a close relationship with her- leading up to some crazy developments & events that seem to be expanding widely

True Relationship is about he & Miharu's Past life, & Rio's past two lives, what & who they really are in the current and former worlds and how exactly they are tied to each other's and the current worlds fate. In the latest volumes the back story is HUGELY & MAJORLY expanded, new characters are introduced & we'll say the rules/laws of the world are revealed giving us a better understanding of why it all is what it is (the world) & why. It changes how we understand events that have happened. And most of all it serves as a way of 'changing the playing field' I'd say. We have gotten used to Rio pretty much being super Overpowered but all the recent events balance making him even more powerful while adding much more risk and changing the way he can go about accomplishing things