@Ronye
it's exact;y her caring and helpful nature that makes him think that. Not sure if I'm alone here but those would be at the top of the list when looking for a partner.
To me thinking someone's going to be a good wife because of their caring nature would be a comment made towards a young adult at the very least. A grown man saying that about a child he barely knows, just met, and is not related to in any way is uncomfortable.
The situation doesn't even need that kind of comment from him since she's done nothing wife relayed in the first place. She was caring and kind, as most children are, he should have just said she was a good kid from what he could tell.
And many people can be kind and caring without being a wife, so why does his mind specifically jump to wife. Even if she were cooking, cleaning, and taking care of the house in place of her sick mother and he saw it he'd probably make the same terrible comment when she's really just a pitiful child force to be an adult from our perspective.
It's probably just terrible writing to justify when he helps her out and to show her gratitude she for some reason asks for Marriage or confesses.