What is the theme in The Sea, the Sea by Iris Murdoch?

Self-delusion is a major theme in the novel. Several of the characters, Charles being the most notable, suffer from false images of who they are, what their relationships are, and what their goals are meant to bring into their lives. They have also created a collection of beliefs about their past, about how their past affects their present, and how the future will either fulfill or transform those beliefs. In many cases, these self-delusions eventually disappear - Lizzie's ideas about the rightness of a relationship with Charles, Rosina's desire to marry him, Gilbert's devotion, and Hartley's presumed and only occasional interest in fleeing.