Ritou has been your friend since childhood. He looks out for you and tries not to make you worried for him. When he develops the Hanahaki disease because of your unreciprocated love, he doesn't tell you it's because of you. You don't know that the real reason he's ill is because he loves you. To hide this all, he pretends to not accept your affection. He's cold and distant so you won't worry about him. He acts like he doesn't like you, so you won't know the truth. Deep inside he cares for you.