This article investigates the process of social forgetting by relating it to the disintegration of social and spatial networks. Looking at the case of Sulina, a small town on the eastern edge of the Romanian Danube Delta, we analyze how the unraveling of networks caused a process of social forgetting with margin-specific features, a fundamental restructuring of social memory and social identities. An important focus of our investigation is the connection between social memory and spatial planning, as a coordinated effort to look forwards. While forgetting as such is seen as a positive process, constitutive of memory, its local characteristics can create problems, for example, for cooperation and planning. Theoretically, this article adopts a systems theoretical framework, incorporating notions derived from anthropology and geography. Social memory is defined as a continuous process of selection, carried out in various specialized subsystems. Concepts of social identity and network are found to be essential in a localized analysis of social memory. Concluding, we argue that local characteristics of social memory can impede the articulation of viable spatial planning strategies.