Background: Life-threatening illness affects both patients and spouses, and spousal caregivers report high levels of distress. Webbased interventions could benefit spouses' and patients' needs and shared everyday life.

Aim: To explore how a family caregiver-targeted web-based psychoeducational intervention influences couples' experiences of sharing everyday life at home while facing life-threatening illness.

Design: This qualitative sub-study involved dyadic interviews with couples (spouse-patient) where the spouse was allocated to the intervention arm of a randomized controlled trial evaluating a web-based family caregiver-targeted intervention. Data were analyzed using Interpretive description.

Setting/Participants: Participants were recruited from five specialized home care services in Sweden. In total, 32 participants, spouses (n = 16) and patients (n = 16) were interviewed as couples after the spouse had accessed the intervention for 4 weeks.

Results: Couples described how the spouses' access to the intervention had provided knowledge that enhanced the couple's understanding of each other's strategies for managing the impacts of the illness. The topics covered in the intervention prompted the spouses to initiate conversations that helped couples maintain a sense of mutuality. The intervention provided support to balance the tension between previous and new relational roles, which had changed due to the patient's illness.

Conclusions: Altogether, the results show that the benefits of family caregiver-targeted interventions may extend from spouse to patient, facilitating their everyday life. Our findings complement previous intervention evaluations by providing insights into how they may be effective. The goal should be that interventions potentially benefit patients and family caregivers.