..

I see it as a type of sickness. They aren't cured at the end--though there is healing of some things. It's still dependence. It's still a love that's effed up. But at least they are grown up and can do what they want. As long as kids aren't getting used, whatever.

I think they found the only way they could "work." The dependence on Yui's part is profound and was set in childhood. He wasn't gonna break out of that binding. He had to be with Kei. So, he found a way to make Kei function enough to be with him. They are both messed up, but at least they found a way to be messed up together and happier.