What part of the plot does chapter 7 “sansara” belong to?

Are you referring to the chapter title Samsara?

Years have passed and Siddhartha is a very rich man, with his own house and servants. Acquisitiveness--the desire for possessions--has clearly overcome him. Yet, he also has contempt for riches, as he did as a young man. He plays games of dice, in which he loses thousands and wins thousands, and becomes hardened and mean. Deep within him, though, Siddhartha still holds many of the values he learned from his father and from the Samaras in the forest. Also deep within him, weariness and sadness grow.

One night Siddhartha has a very frightening dream. He awakes with overwhelming feelings of sadness and decides to give up his life of excess and concerns about money. He leaves, giving up all his possessions and his association with Kamaswami, Kamala and the others. Soon after, Kamala finds out she is pregnant with Siddhartha's child.