[ He bites his bottom lip, because a part of him also wanted to let go of Kido because she wanted to go back home and die with her family there. It was her wish and he wanted to respect that. But another part of him wanted Kido to be with him and not go back to being permanently dead back home. He spent over forty thousand years missing Kido, Rei, and his friends. He cried a lot about it. He was lonely. ]

You're saying that she'll grow, but she can't do that on her own. People grow and change with other people, not by withdrawing into your shell and letting your Shadow do all the work. People are driven away by that, which is what you want. When people typically say "growing as a person", it means something positive. Her family back home helped her grow into the person she is now, isn't she? She's already a strong person. She tries her hardest when it matters and doesn't give up. When she falls and needs help getting back up, her friends are there for her to help her back on her feet. People can still be kind and strong! They don't have to choose one over the other!