Xiao Xin's animation is impossible to grow up and get married, but there is an interesting episode in the animation:

Paragraph 363 (broadcast in Japan on 7 July 2000)

The third story, Taiwan Province, is entitled What Is My Bride?

This story happened after attending teacher Ji Yong's wedding. Xiao Xin dreams of marrying Nana. Of course, Xiao Xin is still five years old. The fictional plot is very interesting. Nana married Xiao Xin and lived together, but Nana's father suddenly appeared and made many rules for Xiao Xin. They are both very interesting. This may be the only story that shows Xiao Xin and Nana getting married.

But unfortunately, this episode can't be seen in the mainland and online. It was broadcast on Taiwan TV before.