Forrest continues living in her mother's house. One day, Jenny suddenly arrives at the house, in the middle of Forrest mowing his lawn. He runs towards her and they hug. Jenny goes directly to sleep "like she hadn't slept in years." She stays with Forrest for a while, and he tells her about everything he's done. "I did all the talking," Forrest narrates.
We see the duo on a walk in town. Suddenly, Jenny spots the house she grew up in and looks stricken. She wanders towards it and throws rocks at it, angrily. When she collapses on the ground in tears, Forrest wanders over to her and sits beside her. In narration, Forrest says, "Sometimes I guess there just aren't enough rocks."
We see a montage of Jenny and Forrest living together in Greenbow. Forrest puts fresh flowers in her room every morning and she buys him running shoes. We see them in the living room, Jenny teaching Forrest how to dance. One night they watch fireworks next to a pond.
One night, Forrest asks Jenny to marry him, but she tells him that he doesn't want to marry her. "Why don't you love me, Jenny? I'm not a smart man, but I know what love is," Forrest says, before walking out onto the porch. That night, in the rain, Jenny comes to Forrest's room and climbs into bed with him. She tells him she loves him, kisses him, and they have sex.
The next morning, Jenny sneaks off in a cab without saying goodbye while Forrest sleeps. When he awakes to find her gone, he is heartbroken, but decides to go after her, running across America in search of her. He runs to Santa Monica, and then back all the way to Maine. He continues to run all over the country, growing a beard as the seasons and landscapes change around him. After he runs for long enough, the news stations begin to report on Forrest's journey, and Jenny sees him on television at her waitressing job.
"Why are you doing this?" a newscaster asks Forrest, and he replies, "I just felt like running." After a while, people begin to join in his running, following behind him, inspired by his gesture. Eventually, in the middle of the desert, Forrest stops, turns to his followers, and says, "I'm pretty tired. Think I'll go home now."
Back in Greenbow, Forrest gets a letter from Jenny asking him to come to Savannah to see her. The scene shifts back to the present, and Forrest tells his bench companion that he's in Savannah now to see Jenny. His companion points him in the direction of Jenny's house and he runs off to find her.
When he arrives, she opens the door for him and hugs him. She takes out a scrapbook of the clippings from his running exploits and apologizes to him for ever hurting him. "I was messed up for a long time," she says, when suddenly there's a knock on the door. A woman is standing there, and a small boy runs to Jenny. Jenny turns and introduces the little boy to Forrest, telling him that he is the father, and that the boy is named after him.
Forrest is shocked and silent, and gets very worried that his son is stupid like him. "He's very smart. He's one of the smartest in his class," Jenny says, as Forrest weeps. Forrest goes into the next room and talks to his son, who is watching Bert and Ernie.
Later, at the playground, Jenny tells Forrest that she's sick. "I have some kind of virus, and the doctors don't know what it is, and there isn't anything they can do about it," she says. Forrest offers for her to come live with him, and she asks him to marry her.
The scene shifts to Forrest and Jenny getting married in his backyard. As they prepare to go to the ceremony, Lieutenant Dan arrives, now with prosthetic legs, and introduces Forrest to his fiancée, Susan. Forrest and Jenny get married in a small ceremony.
Later that fall, Forrest takes care of Jenny in her sickness, bringing her breakfast in bed. One morning she asks him if he was scared in Vietnam, and he suggests that sometimes he was scared, but when the rain stopped and the stars came out, he'd feel better. He details the comforting aspects of nature, in Vietnam and in his running travels. "I wish I could've been there," Jenny says, and he replies, "You were."
Jenny dies, and Forrest buries her under a tree in the backyard. He addresses her grave and tells her that he had her father's house bulldozed, and that Forrest Jr. is starting school soon. Forrest takes out a letter that Forrest Jr. wrote for Jenny and leaves it next to the grave. "I don't know if we each have a destiny, or if we're all just floating around accidental-like on a breeze. But I think maybe it's both. Maybe both is happening at the same time, but I miss you, Jenny," Forrest says, weeping. As he walks away from the tree, a large group of birds begin chirping at once.
Forrest drops Forrest Jr. off at the bus for the first day of school. He gives Forrest Jr. Curious George, his favorite book, to bring into school. As little Forrest gets on the bus, Forrest calls to him and tells him that he loves him. The bus driver is the same one as when Forrest Sr. was a child. The camera pans down to a feather on the ground beneath Forrest, which flies into the air on the wind.
Jenny seems to want to live an easier and more stable life when she returns to Greenbow to stay with Forrest. For the first time in the film, she accepts Forrest's unconditional love and acceptance, and stops running towards self-destructive situations. She is quieter and more receptive to Forrest than she has been in the other parts of the film, and for a moment it seems that perhaps the two childhood friends might be able to save one another from loneliness and keep each other happy.
Jenny is still plagued by personal demons that she never addresses directly, however. The trauma of abuse from her father has left an enduring scar from which she can run but not hide. When she and Forrest visit her childhood home, she is overcome with anger and begins throwing rocks at the house until she ends up weeping on the dirt road in front of it. Time and time again, she is overpowered by the pain of the memory of her mistreatment, and struggles to heal.
The mythic proportions and stakes of the film continue when Forrest goes in search of Jenny. He runs across the entirety of the country, from Alabama to Santa Monica to Maine. Forrest's single-minded journey is the stuff of fables, an unbelievable act of commitment and desire for Jenny that lightens the mood of his recent heartbreak. Instead of wallow, the simple-minded Forrest throws himself into an activity as though he were a religious man on a spiritual quest.
Jenny's fate becomes even more tragic when she finds out she has contracted an unknown and deadly virus. After introducing Forrest to his son, Jenny tells Forrest about her sorry future. Try though he did to protect Jenny from danger, Forrest is unable to prevent Jenny from going down self-destructive rabbit holes, the likely cause of her disease, which seems to be HIV. It is unclear when and how Jenny contracted HIV, a sexually transmitted and inheritable disease, without also passing it along to Forrest and Forrest Jr., but Jenny's fate is her own.
While the film passes through exceedingly tragic scenarios, it never dwells in tragedy for long, often pivoting to a more positive sentimentality soon enough. Perhaps this tonal pivoting has something to do with Forrest's limited cognitive abilities, his tendencies to see life events in terms of basic aphorisms and easily digestible increments. This sentimentality makes Forrest wiser than expected, a man who is able to ride the ebbs and flows of life with relative ease, but also with a sense of gravity and meaning.