"True love" describes the deep love a couple has for each other under sometimes difficult circumstances. The girl, being a genius, has different aims from the slightly above-average boy, but their concerns are always for the happiness and accomplishment of each other. Although they were not overtly religious, their Christian backgrounds influenced their lives importantly, affecting how they approached their worlds of engineering and college.
True Love also deals with the adjustment the United States was facing after World War II. The ways society thought about women's issues were changing, and this is part of the story.