In "About a Boy," Nick Hornby raises questions about the complexity of human relationships and the choices individuals make. He suggests that some people unnecessarily complicate their lives when they could instead embrace simplicity and ease, much like solving a straightforward math problem.
The quote reflects the idea that risking emotional vulnerability, such as liking someone or allowing oneself to be loved, requires favorable conditions. If the circumstances aren't supportive, it may be better to avoid the complications that come with unreciprocated feelings and emotional entanglements.