For a moment, Kiyohira doesn't know how to respond.
5 years ago, her father told him that it won't be easy to love her. Kiyohira was sure that love was enough to be with her. It's clear that it's not.
In a way, she loves him too. But she doesn't know how to love him with the broken parts of her. Compare to loving her son or her father, loving him is most difficult for her.
She was broken by the world. Even he played a part in that unconsciously. He didn't even know that she was envious of his life. His father, Kamiyama Hitomi, Takeuchi Seiji, and even he owe her.
He knew that it would be challenging to be with her. When Chisa's threat became clear, he was afraid at that time when he kept her inside the house. He couldn't protect her many times. Even at the end, Chisa nearly won.
Sorry for the late chapter~ I was finishing other pending novels first.
I like the concept of Kintsugi a lot. The broken is beautiful. It's my favorite one among all the untranslatable words. There was another one - Saudade - The love that remains (it's the title of one of my novels here).
There are other concepts. If you don't know, try searching untranslatable words.