The central aim of this longitudinal observational study was to test whether patients with a high need for emotional expression are especially sensitive to their partners' responsive behavior, and therefore at risk for depressive symptoms when responsiveness is withheld. Patients with colorectal cancer and their partners (n = 58) participated in a longitudinal study (3, 5 and 9 months after the diagnosis). Additionally to self-report measurements (i.e., patients' need for emotional expression, patients' depressive symptoms and patients' relationship satisfaction) couples were videotaped discussing cancer-related concerns. External observers coded partners' responsiveness (i.e., understanding, validation and caring) and patients' self-disclosures. Partner responsiveness predicted lower levels of depressive symptoms over time in patients who had a relatively high need for emotional expression above and beyond the effect of relationship satisfaction. We demonstrated that partners' understanding and validation are more important in explaining patients' depressive symptoms than partners' caring behavior. Our findings highlight the importance of the relational context in improving adaptation to cancer taking into account individual differences.