In the nevel, all the characters face obstacles. But I want to focus the quagmire that Macon Dead Jr.'s family faced. As Sitkoff mentions in the book that wealthy black people couldn't mingle with the whites due to their color of skin and also their self-esteem prevented them from interacting with the black lower community.
Macon's family enjoyed their advatage of wealth; they owned their own house, had a car, and even the job of Ruth's father and Macon's position being landlord intimidated the fellow black communiy. But the problem was that even though they had higher living standard than most of black people, their skin color was black so didn't really have advantage. Although Ruth's father was a well known doctor, Ruth could only, out of her 3 labors, deliver Milkman in the very own hostipal that her father worked in. Milkman, with guitar, was stopped and was caught while running away with green sack they stole from Pilate just because their skin color was black. Only when Macon payed money, Milkman was released. Also by the clothes and the way they acted, we can know that they tried to look like white but it was impossible to overcome their skin color.
When Magdalane called Lena wanted to have relationship with Henry Porter, Macon's self-esteem of being higher class than Porter prevented him from letting Lena have the relationship. Also in early stage Milkman couldn't mingle with the lower black community, until Guitar helped him out.
Even though only few whites appear in this novel whole concept of segregation is rooted in the background of the novel.