If Riku knew that Sora was embarrassed, he might be a little hurt. As it was, he appreciated his love's gentle attention and kindness. He was having such a bad time of all of this, he appreciated Sora's willingness to put up with his behavior when he needed him the most. He could handle social issues, rudeness, pain, hard labor, dirt, uncomfortableness, but family issues? He just fell apart and became the angry, lost eight year old again.
He didn't know HOW to even begin to start explaining it to his brother in a way that wouldn't make him angry.
"Well you are the one who said this is the most important thing I have to do today," Corin grumped a little. He reached out to touch his brother's shoulder, and Riku just burrowed in further. "What... causes this?"