Hearts Divided examines the growing centrality of political beliefs and identities in personal life. Focusing on cross-cutting romantic relationships-partnerships in which individuals hold opposing political views-the book explores how political difference reshapes both personal relationships and democratic engagement.Set against the tumultuous period from 2020 to 2024---marked by two presidential elections, a global pandemic, an insurrection, and an assassination attempt---Hearts Divided investigates what happens when politics enters the most private corners of life. Why can disagreement between partners feel so destabilizing? When does it threaten the relationship itself?Drawing on in-depth interviews with individuals in current and former cross-cutting relationships, alongside survey data from politically mixed and politically aligned couples, the book shows that cross-cutting partners face distinctive relational and emotional challenges that shape both their private lives and their civic participation.At the center of the analysis is the moralization of political identity. When political differences are interpreted as moral failings, disagreement becomes a judgment of character, often rendering relationships untenable. By explaining how political moralization has intensified and offering practical strategies for navigating disagreement, Hearts Divided illuminates what intimate conflict reveals about our contemporary politics---and what sustaining relationships across difference may mean for democratic life.