Materialism, or beliefs and values that link wealth and consumption to success and happiness, negatively affects interpersonal relationships. Prior work has typically explained these effects through the allocation of personal resources (such as time or money) within relationships, thus using a behavioural route. However, this research proposes an alternative cognitive pathway to understand the adverse effects of materialism on interpersonal relationships. Three studies (N = 1389) employing correlational and experimental methodologies showed that materialism leads to heightened expectations and standards for a significant other, which are associated with poorer interpersonal outcomes. Specifically, materialism heightens the ideal standards that one has for a close other around achievement (e.g., ambition) and positive image (e.g., attractiveness), which are linked to higher conflict and lower relational satisfaction. Therefore, this work contributes to deepening our understanding of how consumer‐oriented values shape social perceptions and negatively affect interpersonal dynamics. Practical applications include informing relationship counselling practices, developing educational interventions, and guiding marketers and media content producers towards messages that do not increase individual's ideals and standards for themselves and others. Further research should explore other factors that might alter this mediation (e.g., mindfulness) and examine the short‐ and long‐term effects through longitudinal and interventional‐based research.