Purpose This study aims to investigate the impact of Restaurant Week participation on online engagement, exploring the tension between relational and transactional review behaviors. Design/methodology/approach Grounded in the social exchange theory-equity theory (SET-ET) framework, this study analyzes a longitudinal Yelp data set from Houston (2007–2019) using a difference-in-differences approach to identify the causal offline to online effects. Findings Participation in Restaurant Week drives a surge in review volume but a concurrent decline in review helpfulness. The SET-ET framework explains the “Restaurant Week Paradox”: promotional scarcity triggers the reciprocity norm, while the discount frame simultaneously activates a transactional, effort-minimization heuristic. Further analysis reveals that first-time reviewers and locals drive this engagement trade-off, whereas returning patrons and tourists maintain cognitive depth. Fine-dining establishments incur a more severe utility penalty than casual-dining establishments. Practical implications This study offers strategic pathways to preserve digital review utility. At the micro-level, managers should adopt product-based framing and dynamic inventory allocation to maintain service standards. At the macro-level, destination marketing organizations should implement tiered participation guidelines to protect brand equity. Originality/value This study advances relationship marketing by establishing event-based promotional scarcity as a theoretical boundary condition within the SET-ET framework, demonstrating that digital reciprocation is contingent upon a consumer’s relational proximity rather than solely on the economic deal.