OBJECTIVE: The aim of this study was to describe decisive situations experienced by spouses of patients with heart failure that could potentially affect their ability to provide social support to the patient. METHODS: A qualitative descriptive design with a critical incident technique was used. Twenty-three informants, 15 women and 8 men, who were spouses of patients with severe heart failure were strategically chosen to ensure maximal variation in sociodemographic data and experiences as a spouse. RESULTS: Decisive situations influenced the experience of spouses of patients with heart failure in a manner that was either positive (involvement with others) or negative (feeling like an outsider). When spouses were given attention and treated like persons of value, they experienced involvement with others. In these cases, spouses had someone to turn to and were included in the physical care. In contrast, when spouses were kept at a distance by the patient, were socially isolated, and received insufficient support from children, friends, and health care professionals, they experienced feeling like an outsider. CONCLUSIONS: By identifying spouses' experiences, health care professionals can assess which kind of specific interventions should be used to improve the life situation of the patient with heart failure and his or her spouse.