we all have a hunger

The obvious loss is Zhang Haixia, it's a devastating event that shakes Zhang Haiyan to his core, that grief colors a good chunk of the story. But Zhang Haixia carries so much more with him when he dies, Zhang Haiyan's childhood, his home, everything he thought he was is lost at the same time

Xiamen is home to the two of them, a home they long after for 10 years and expect to not see for another 20. Zhang Haiyan gets the chance to return, but when he arrives he finds that the southern archives that he expected to find there never existed in the first place. Many of the things in his life growing up were actually lies and the place he wanted to go back to, that he wanted to go back to WITH Zhang Haixia, was gone. The temporary home he had in Malacca was also gone, without Zhang Haixia there was no point to go back

On top of all these profoundly destabilizing events, he also gets the revelations from Zhang Haiqi about what the Zhang family actually is, he has to readjust his whole world view with barely any breathing space

In the end, Zhang Haiqi is the only thing he has left that offers him some certainty (despite the foreshadowing, i'm taking the crumbs, she's still alive!!)