Why didn't Cheng Xiao marry the protagonist in his life?

In his speech, the author said that it is the first love for the protagonists in pairs, and the first love is generally beautiful and cruel. The life behind the protagonist is quite dark. What he needs should at least be the support of a mature woman like Xu. This is my personal guess.

In fact, from the perspective of writing, the author failed to find it from the beginning to the beginning and then to Shenzhen. Actually, I think the ending of the last two people not being together has been buried.

However, the timeline of the article is too short. If the span is a little bigger, the chances of writing a harem with income of three to five years are still quite large.