What could he possibly have to say to that man? Ryuutaro didn't understand, but when it came down to families there were a thousand things he didn't understand. Even if he could grasp the concepts, the emotional reasoning remained entirely unfamiliar to him.

"If you say so..."
'Promise you don't disappear' was something he wanted to say but didn't. It would've been a silly and childish thing.
Instead he helped his boyfriend in silence, worry still obvious on this face.