The phenomenon of shared intention has received much attention in the philosophy of mind and action. Margaret Gilbert (1989, 2000c, 2014b) argues that a shared intention to do A consists in a joint commitment to intend to do A. But we need to know more about the nature of joint commitments to know what exactly this implies. While the persistence of joint commitments has received much attention in the literature, their impersistence has received very little attention. In this paper, we shed light on the impersistence of joint commitments by showing how joint commitments can be dissolved by unexpected events.