I gave my hot take on Genki once here in the gossip thread.
What i wrote there is probably not everything, but seeing how Genki is loosing friends right and left, rememberd me of a common problems of his disorder.
That would also explain maybe why Ryoga might have distanced himself from Genki too.
On another note, was they friends in private? or did their bands just often perform together?
Does he hang out with anyone else than the Ryutaro dude?