Jenny runs away from Forrest not because she doubts his love, but because her profound childhood trauma makes her feel completely unworthy of it. The film establishes early on that Jenny was severely sexually abused by her father in their dilapidated farmhouse. This trauma instills a deep-seated self-loathing and a belief that she is damaged goods. When she looks at Forrest, she sees absolute purity, innocence, and goodness. To accept his love would require her to believe she deserves it, a psychological leap she cannot make while still processing her past. Instead, she seeks out destructive relationships and chaotic environments that mirror her internal sense of brokenness, running away whenever Forrest offers her a glimpse of genuine, unconditional safety because it terrifies her. Every time she leaves, she is protecting him from what she perceives as her own toxic influence. Her ultimate return to Alabama only happens after she has hit rock bottom, contemplated suicide on a hotel balcony, and finally begun the painful process of healing, symbolized by her throwing rocks at her father's ruined house. Only when she has begun to dismantle her past trauma can she finally allow herself to be held by Forrest and accept the domestic peace she spent her entire life running from.