This manga should settle for one thing or the other. Kasumi either loves Sakurako or doesn't. It won't change a thing about them regardless, so why bother? Unless a sudden verbal declaration from Kasumi will make them act more physically. Which it won't. I'm not sure if the author is running out of ideas, if this was planned, or if it was due to them being prodded about this "issue" but it's such a redundant "plot", especially this late into the series.
This whole philo-Kasumi is the only thing that I ever found annoying about the manga. Sure, people had longwinded discussions if it's love or not, but does it matter? Again, Not really