I see why many people thinks that Ruka is a troublemaker, which is somewhat true in all honesty. But think again, Kazuya always runs from his problems. He can always choose a way to settle everything starting from the rental situation. With that done you can face Ruka. And finally, maybe you can truly go out with Chizuru?
But hey, Kazuya's cowardice and escapist behavior is the series's highlight after all. About 80+ chapters in and that should be the common fact at this point.