Secrets
A number of characters keep secrets from each other throughout the novel: Roy hides from Celestial the fact that Big Roy isn't his real father, which she is upset about, and Celestial initially hides from Roy that she is falling in love with Andre. Secrets prove a point of tension between characters and cause a number of arguments, which leads to the disintegration of a number of relationships.
Racism
Roy is falsely falsely convicted of rape because the American judicial system is prejudiced against him as a black man. There is no evidence against him besides the elderly woman's testimony, who later realizes that she was too traumatized to give an adequate testimony. An American Marriage reveals the destructive impact that racism has on people, as it leads to characters being imprisoned for crimes they didn't commit, and also reveals how ingrained racism is in America, because Roy's false conviction does not come as much of a shock: the characters are already aware of racism's prevalence.
The Destruction of Relationships
An American Marriage explores how relationships dissolve in traumatic and difficult situations. Roy and Celestial's marriage cannot withstand a lengthy prison sentence and they eventually divorce. Celestial's relationship with her parents deteriorates in response to this divorce because they feel that she is abandoning her husband. Roy's relationship with his father also deteriorates after he leaves prison, because they cannot figure out how to adjust to life after Roy's mother's death. Relationships between characters inevitably change after traumatic and harrowing circumstances, and often those relationships crumble and cannot be fixed.
Family
Characters find family in different people, and that changes over time: Big Roy might not be Roy's biological father, but he views him as such, and they have a close family relationship. While Roy is in prison, he finds familial comfort in his biological father, even though the two had no relationship before. Roy and Celestial consider having a family together, but when that doesn't work out, Roy has children with Devina, which allows him to have a family even if it wasn't what he initially expected.
