The "Kiss Quotient" is a concept introduced in the novel by Helen Hoang, which explores the complexities of romantic relationships. It centers around the idea that individuals have different levels of experience and comfort with intimacy, particularly in kissing. The protagonist, Stella Lane, is a successful woman with Asperger's who decides to improve her romantic skills through a unique approach. In the story, Stella hires an escort, Michael, to help her learn about physical affection and emotional connection. The narrative highlights the importance of communication and understanding in relationships, emphasizing that everyone has their own pace and preferences when it comes to love and intimacy.