What is meant by the point of view?

This rocky canyon in the desert is not the deepest canyon or the whitest which best identifies the adjective phrase

Then she heard his step on the stair away down on the first flight, and she turned white for just a moment. the phrase "she turned white for just a moment" is mainly used to show that della has very fair skin. is afraid of jim's reaction. is beginning to get an illness. had become extremely angry.

Who is ¨ the guilty party¨ at the end of the text, and how do his actions contribute to the storys theme?