Background <p>Family support is central to amyotrophic lateral sclerosis (ALS) care. Spouses often assume the role of primary caregiver, facing daily challenges as their partner’s needs progressively increase. Younger ALS caregivers appear to have distinct experiences and needs, yet age- or life-stage variations and processes of caregiving are seldom considered in studies of ALS family caregiver experience.</p> Methods <p>We undertook a qualitative study, guided by constructivist grounded theory methodology, to explore the dynamics of family caregiving following an ALS diagnosis in a younger middle-aged family member (≤55 years). Data were coded to identify psychosocial processes, including how family caregivers engage in caregiving.</p> Results <p>In-depth interviews were conducted with ten spousal caregivers between August 2023 and August 2025. Overall, our theoretical understanding of spousal caregiving for younger middle-aged adults with ALS (YMAs) was captured by the core category ‘straddling two worlds,’ reflecting how caregivers navigated multiple interconnected dichotomies: present and future, familiar and new norms, current and anticipated losses, and the worlds of the living and the dying. To contend with an uncertain future, caregivers anchored themselves in the present as they navigated a shifting sense of normalcy. Middle age expectations and social norms shaped how caregivers engaged in caregiving and experienced losses that were often unending and ambiguous.</p> Conclusions <p>Caregiving for a spouse with ALS in younger middle age involves temporal, practical, emotional, and existential processes. Caregivers of YMAs may benefit from interventions that help them tolerate uncertainty, stay grounded in the present, maintain normalcy, and grieve losses throughout the caregiving trajectory.</p>