Although mobility in and out of intimate relationships has become more common in later life, it has been a neglected issue in social gerontology. In this article, we ask what characterises the formation of new intimate relationships in later life, and whether there are any specific conditions that separate these from relationships in earlier stages of the lifecourse. On the basis of qualitative interviews with 28 persons aged 63-91 who have established a new intimate heterosexual relationship after the age of 60 or who are dating singles, we argue that time constitutes such a central structuring condition. We discuss and theorise two aspects of time - post-(re)productive free time and remaining time - which have an important formative power on new late-in-life relationships. We argue that together these aspects form a central existential structure of ageing in many Western societies - the paradoxical condition of having lots of available free time but little time left in life - which, besides influencing new late-in-life relationships, might also be relevant to other aspects of and choices in later life.