(Title withdrawn - for peer review)

Despite the development of numerous constructs to characterize, explain, and predict relationship quality – the foremost studied outcome in relationship science – the boundaries of these constructs remain poorly defined. As a consequence, research has yet to clarify which relationship constructs should be treated as facets of relationship quality and which should be treated as independent predictors. The goal of the current research was to assess the degree of empirical redundancy among measures of prominent relationship constructs using bifactor modeling techniques and standard data collection methods (i.e., self-report). Across two studies involving census-matched, national panel samples of individuals in romantic relationships (Study 1: N = 2,000; Study 2: N = 1,439), we administered representative measures of the most-studied relationship constructs used to predict or explain relationship quality. In both studies, results showed robust evidence that a single general factor (Q) accounts for most of the common variance across items, and limited evidence of any reliable specific factors beyond the influence of Q. These preliminary findings raise concerns about the conceptualization and measurement of distinct constructs in relationship science, and widespread use of self-report methods to capture meaningful aspects of relationship functioning. The proposed Study 3—a Registered Report—will aim to address key methodological limitations in Studies 1 and 2 using a more robust and representative study design.