Abstract
<p>Obsessive thinking about a loved one (i.e., constant, involuntary, repetitive thoughts about the loved one) is a defining feature of romantic love yet remains markedly under-researched. This article provides the first review of obsessive thinking about a loved one in romantic love, organising the disparate literature using an "Eight Perspectives" approach spanning evolutionary history, evolutionary functions, development, mechanisms, ecology, cognitions, emotions, and behaviour. We argue that obsessive thinking about a loved one likely emerged by co-opting mother-infant bonding circuitry, appears across cultures and across the lifespan, and may have evolved to promote proximity-seeking and sustained orientation toward a loved one. Contrary to long-standing claims, the mechanisms underlying obsessive thinking in romantic love are unlikely to be shared with obsessive-compulsive disorder. People who are in love think about their loved one for approximately 50% of their waking hours, and this thinking is associated with romantic (but not companionate) love, distraction, proximity-seeking behaviour, and analgesia. Whether such thinking is experienced as bothersome or enjoyable depends less on its frequency than on companionate love and reciprocation. We conclude by identifying priorities for future research across all eight perspectives.</p>