Although palliative care nurses are identified as key players in supporting couples during advanced illness, there is a lack of evidence about their knowledge and experiences with this particular role. The aim of the study was to explore palliative care nurses’ attitudes, roles, and experiences in addressing relationship functioning of couples in daily practice. A qualitative study was conducted using in-depth interviews, observational research, and peer debriefing groups with palliative care nurses in Flanders, Belgium. Nurses support relationship functioning by creating a couple-positive care environment, by being present/acknowledging feelings, and by rectifying imbalances between couples. They do so in a proactive way, backed up by team support. Nurses hesitate toward explicitly unraveling and intervening in relationship problems, in favor of providing comfort or offering a strengths-based approach. The findings offer an urgent call to enhance the educational programs for palliative care nurses by integrating the theories and practice frameworks that guide relational assessment and intervention, which are being used in family nursing.