The themes in the book "Separating" by John Updike include marriage, infidelity and the tension that arises from trying to recapture lost youth. "Separating" is part of a short story collection called "Too Far to Go." The stories track the evolution of a young couple's marriage.
"Separating" recounts how Richard and Joan Maple explain to their children that they are separating. The themes of marriage and infidelity are built up throughout the course of the short story collection. However, in "Separating," Richard finally takes responsibility and makes the decision to leave Joan. Prior to "Separating," Richard tries to continue relationships with both his wife and his mistress.
The story also uses Richard's character to discuss the reasons behind infidelity. Updike alludes to the notion that Richard is willing to separate from his wife of nearly 30 years because he wants to reclaim his lost youth. Many of Updike's works examine the institution of marriage and those who were participating in it during the 1960s and 1970s. The same is true in "Separating" with the Maple couple, who were married in their early 20s. Richard's attempt to find his lost youth can be interpreted as Updike's own discussion on the impact that getting married so young has on a marriage in the long term.