This study extends the Job Demands-Resources (JD-R) framework by proposing JD-R 3.0, which explores the dynamic and nonlinear relationships among Work Connectivity Behavior After-Hours (WCBA), Perceived Organizational Support (POS), and employee outcomes, with a specific focus on psychological contract violation (PCV) and psychological distress. Data were collected from 625 employees in a large financial organization in China across two waves, and polynomial regression and response surface analysis were used for hypothesis testing. The results reveal that in incongruent scenarios (where WCBA is high and POS is low) employees experience significantly higher levels of psychological contract violation and psychological distress. In congruent scenarios, where both WCBA and POS are aligned, POS acts as a buffer, mitigating the negative effects of WCBA on distress. However, the protective effect of POS diminishes beyond certain thresholds, resulting in a "too-much-of-a-good-thing" effect, where high WCBA paired with high POS increases psychological contract violation and distress. These findings advance JD-R theory by emphasizing the importance of maintaining a balance between job demands and resources and introducing the concept of diminishing returns for job resources. The study offers both theoretical contributions to the development of JD-R 3.0 and practical insights for managing employee well-being in the context of constant connectivity and increasing technological demands.