Background: Exclusive enteral nutrition (EEN) is first-line therapy for pediatric Crohn's disease, yet adherence remains challenging. Longitudinal understanding of how children and families adapt over time is limited. Objective: To explore the longitudinal adaptation process of children and families during the first two months of EEN and develop a model explaining divergent pathways. Methods: A longitudinal qualitative study with 25 child-caregiver dyads interviewed at EEN start, 1 month, and 2 months (75 interviews). Analysis employed grounded theory principles through horizontal (within-timepoint), vertical (cross-timepoint), and integrative process approaches. Results: Adaptation unfolded across three phases. Initial Resistance featured emotional aversion and family-enforced compliance. Active Adaptation (1 month) saw health-driven acceptance, coping strategies, and school support. The 1-2 month period emerged as a critical juncture leading to pathway divergence in the Integration or Crisis phase. Successful adaptation involved self-management internalization, peer support deepening, and meaning reconstruction; others faced adherence crisis from untreated taste fatigue and burnout. Seven interdependent dimensions—attitudinal, social support, self-efficacy , barriers, economic, treatment journey , psychological—evolved dynamically across phases. Conclusion: Adaptation to EEN is a nonlinear, processual journey with a key transition at 1-2 months. The developed model explains change mechanisms and pathway divergence, informing dynamic, phase-specific nursing interventions to support integration and prevent crises.