Risako's either blatantly lying at her face, or the author is preparing a huge twist. I'm leaning towards the former, but who knows, it could be red herring.
I like how the story is developing and I don't get the Kaoru hate.
Her world's been crumbling for some time and she's been too scared to face the truth. But she's also reaching her limits now, which is showed through those short outburst (like when she unconsciously asked Risako about meeting Reiichi, or when she snapped at Reiichi in this chapter).
She's finally getting the development she desperately needed, since she was missing for so many chapters. I guess this is my only complaint with the manga, the pacing.
I have absolutely no idea how the situation is gonna evolve, which is what makes this manga engaging for me.