Romantic love seems to be a nearly universal phenomenon, appearing in every culture for which data are available and in every historical era. This chapter first reviews research on how ordinary people construe love. Then it turns to how researchers have understood and measured love, organizing its discussion around the theme of types of love. Next it covers the course of love with a focus on falling in love. It then reviews several approaches that have been particularly influential in specifically focusing on understanding the dynamics of romantic love, especially with regard to passionate love. It concludes with a brief review of the work on other kinds of love in relationships. The authors hope that this review has conveyed their view that the study of love is both important and a thriving scientific endeavor, offering both a solid foundation and vast opportunities for significant future work.

This chapter describes positive interpersonal processes: interactions between people that actively enhance their close relationships. It begins by describing the field’s shift toward studying positive processes and highlighting the utility of considering positive phenomena as unique from negative phenomena. Then, it reviews three interpersonal behaviors that have been shown to enhance relationships and describes the evidence supporting their benefits. First, spending time together (particularly spending time on novel and exciting activities) enhances relationships by enabling partners to meet their self-expansion needs in ongoing relationships. A second positive process is co-experiencing positive emotions, such as joy, amusement, and excitement, which augment and sustain positive experiences and facilitate interpersonal synchrony. Finally, this chapter reviews the benefits of communicating affection and the individual differences in how and how often people express affection.

This chapter examines how early relationships become established relationships. It reviews varying relationship trajectories (e.g., ascent, peak, and descent) and then describes the three key components of the relationship that develop over time: love, intimacy, and commitment. First, the chapter defines and differentiates the various forms of love (e.g., passionate love, companionate love, compassionate love) and reviews how love develops and changes over time. Second, this chapter explores how interpersonal intimacy develops through repeated instances of self-disclosure and perceived partner responsiveness and how developing intimate relationships change the self. Third, this chapter reviews how people make and communicate their commitment decisions, as well as how social network members shape commitment. Finally, it provides an overview of common major transitions (cohabitation, marriage, parenthood) and some key challenges therein.