The 16-item Attentive Awareness in Relationships Scale (AAIRS) was created to assess the constructs of mindful attentive awareness toward a romantic relationship and distracted inattention in a relationship. Building on a growing body of work linking mindfulness to dynamic relationship processes and functioning, the AAIRS subscales were specifically conceptualized as dynamic processes that can meaningfully change from day to day or week to week, thereby aligning with newer models of mindfulness like the Unified Flexibility and Mindfulness (UFM) model. This operationalized relationship mindfulness and distraction as new relationship processes. Shorter 8- and 4-item versions of the AAIRS were also developed and validated for use in contexts that could not accommodate a 16-item measure. While related, the AAIRS has shown that the constructs of attentive awareness and inattention/distraction change independently over time. The AAIRS was developed from a pool of 54 items across two large-scale online samples (ntotal = 3861). Items were selected using exploratory factor analyses (EFAs) and item response theory (IRT) analyses to optimize the information provided by the scales. The final two subscales demonstrated: (1) excellent levels of internal consistency that generalized to 32 different demographic subgroups; (2) a stable factor structure across random sample halves using EFA and CFA; (3) strong convergent and discriminant validity with existing scales; (4) increased precision and power for detecting differences between subjects; (5) high levels of responsiveness to meaningful change over time; and (6) unique predictive validity above that of existing scales.