Objectives <p>Having a child is a shared experience where partners influence each other’s adaptation to parenthood. While much research focuses on mother–infant bonding, the impact of partners’ psychological functioning on this outcome is underexplored. This study investigated how mothers’ perceptions of partners’ pre- and postnatal depressive and anxiety symptoms affect mother–infant bonding difficulties and whether mothers’ own symptoms mediate these relationships.</p> Method <p>A sample of 525 Portuguese women (M age = 32.85, SD = 5.13) with infants &lt; 24 months completed an online survey from February to March 2020. Assessments included history of depression and anxiety, current symptoms, perceptions of partners’ symptoms, and mother–infant bonding difficulties. Multiple hierarchical linear regressions and mediation analyses were conducted.</p> Results <p>Women’s current depressive symptoms and perceptions of partners’ current anxiety symptoms were associated with greater bonding difficulties. In contrast, perceptions of partners’ prenatal anxiety symptoms were associated with fewer bonding difficulties. Perceptions of higher levels of partners’ current depressive symptoms were indirectly related to increased bonding difficulties through mothers’ own depressive symptoms.</p> Conclusions <p>Partners’ psychological functioning impacts mothers’ adaptation to motherhood differently across the perinatal period. Perceived prenatal anxiety in partners may serve as a protective factor, whereas postpartum depressive and anxiety symptoms contribute to bonding difficulties. These findings highlight the importance of considering dyadic processes in understanding and supporting parent–infant relationships.</p>