Why do people fall in love? Does passion fade with time? What makes for a happy, healthy relationship? This introduction to relationship science follows the lifecycle of a relationship – from attraction and initiation, to the hard work of relationship maintenance, to dissolution and ways to strengthen a relationship. Designed for advanced undergraduates studying psychology, communication or family studies, this textbook presents a fresh, diversity-infused approach to relationship science. It includes real-world examples and critical-thinking questions, callout boxes that challenge students to make connections, and researcher interviews that showcase the many career paths of relationship scientists. Article Spotlights reveal cutting-edge methods, while Diversity and Inclusion boxes celebrate the variety found in human love and connection. Throughout the book, students see the application of theory and come to recognize universal themes in relationships as well as the nuances of many findings. Instructors can access lecture slides, an instructor manual, and test banks.