Edit Yamcha and Bulma first meet when they are years-old, during Bulma's journey with Goku to collect the Dragon Balls. At first sight, Yamcha is terrified of Bulma because of his fear of women, causing him to madly blush and flee the scene.
Bulma on the other hand is instantly smitten with Yamcha and is eager to pursue him. Ultimately, the two form an alliance to keep Pilaf and his minions from stealing the Dragon Balls and when Goku uses the Dragon Balls for his wish, Bulma and Yamcha are disappointed that their wishes were unfulfiled Bulma wanting the perfect boyfriend and Yamcha wanting to get rid of his fear.
However the two realize they have each other and decide to become a couple. After becoming a couple, Bulma and Yamcha quickly fall in love but their relationship suffers from problems almost right away. After barely half a year, they break up due to Yamcha spending majority of his time training in the wilderness and keeping little to no contact with Bulma. When he returns to visit her, she accuses him of neglecting her feelings but says he will make it up to her which is implied to be sexual intercourse.
They get back together and by all appearances, seem to be a devoted couple, although Bulma frequently attempts to chase other men, whilst blaming Yamcha for not being a good boyfriend.
Krillin asks Yamcha why he bothers putting up with Bulma's rudeness and mistreatment, and Yamcha replies he can't help but like her. After being a couple for five years, they attend the 23th World Martial Arts Tournament after maintaining another long distance period in which Yamcha spent training in the wilderness.
Bulma misunderstoods that Yamcha dated Chichi and she is furious but eventually forgives him. However, upon learning of the inevitable arrival of the Saiyans, Bulma meets with Yamcha to tell him, and Krillin observes that Bulma is still in love with Yamcha.
When the battle with the Saiyans commences, Yamcha is killed and Bulma, who has been watching the battle from television, breaks down into tears. She cries out that she would have agreed to marry Yamcha if he asked her beforehand. After seeing his body, she remembers all the happy times she spent with Yamcha but comes up with a plan with Krillin to resurrect Yamcha and the other fallen Z Fighters by going to Planet Namek and using its Dragon Balls.
A few months later, the plan is a success and Yamcha is resurrected, and shares a happy reunion with Bulma. They resume their relationship but shortly after, she is dismayed when Krillin's girlfriend, Maron, flirts with Yamcha in front of her and he laughs it off despite Bulma's jealousy.
Two years later, their relationship begins to deteriorate when Bulma mentions to Yamcha she had a dream of kissing Vegeta and is worried about him while he searches for Goku in space, which makes Yamcha jealous. Bulma later invites Vegeta to live with her, despite Yamcha's protests due to Vegeta being a former enemy who nearly destroyed the Earth.
After hearing out the upcoming arrival of the Androids, both Yamcha and Vegeta decide to train for the battle, but hearing Goku wishing for Bulma to have a healthy baby makes Yamcha think it is time for him and Bulma to get married and have a family. However, Bulma does't seem interested. Vegeta trains to the point if nearly killing himself and Bulma tends to Vegeta and assures him he doesn't need to prove himself to anyone, leaving Yamcha amazed and disgusted by the closeness between Bulma and Vegeta.
Seeing how Bulma is showing more attention to Vegeta than him, Yamcha becomes increasingly jealous and shows resentment towards Vegeta, whom he blames for interfering with his relationship with Bulma even though Vegeta is unaware of Bulma's growing feelings for him. Yamcha ends up returning to his flirtatiousness with other women and Bulma finally breaks up with him for good, explaining she has gotten tired of tolerating his unfaithfulness. Heartbroken and lonely, Bulma attempts to befriend Vegeta as a source of comfort, but they end up developing a mutual attraction and begin an affair, which results in her becoming pregnant and giving birth to his son, Trunks.
Yamcha is heartbroken that he is not Trunks' father but is angry at Vegeta for ignoring the child, and Yamcha believes Vegeta had taken advantage of Bulma, who denies such a thing. After the battle with Cell, Yamcha is touched by Vegeta's emotional reaction to Future Trunks' death and forgives him, and gradually accepts that Bulma has moved on as she and Vegeta reconcile and get married. Seven years later, Bulma and Yamcha are now close friends and Yamcha still visits her and her family occasionally, which Vegeta seems to have no problem with.
When Vegeta allows Babidi to take control of him and causes havoc to provoke Goku, Yamcha tries to comfort a distraught Bulma and assures her they can use the Dragon Balls to bring back those who died in the chaos. Shortly after, Bulma breaks down when she learns Vegeta died fighting Majin Buu and Yamcha tries to calm her down to no avail.
A year later, during a friendly game of baseball between Universes 7 and 6, Bulma cheers for both Yamcha and Vegeta. She teasingly flirts with Yamcha, who is flustered and Vegeta, slightly irritated and not aware of the rules, beats Yamcha with the ball. Ten months later, Yamcha visits when he learns Bulma and Vegeta's daughter, Bulla, had been born.
Bulma is happy he is visiting and lets him hold the baby but Bulla cries when he makes a funny face and Vegeta is angry at Yamcha for making his daughter cry. Trivia Edit Up until Goku's marriage to Chichi, Yamcha and Bulma were the only couple who had been together the longest.
They dated from age 16 to when they officially broke up at age 32, adding up to the conclusion that their relationship lasted for almost 16 years. Both had spoken of getting married but Yamcha was the one who first suggested it in the Trunks saga, although it was apparent nothing came of it as Bulma stated she had no interest in settling down with him soon after.
Future Trunks claimed the reason for the breakup was due to Yamcha's infidelity.