Betty Ross is the deuteragonist of the film Hulk. She is Bruce Banner/Hulk's ex-girlfriend/co-researcher and General Thunderbolt Ross's daughter.
Betty and Bruce were romantically involved and in love until she decided to break up with him due to his repressed nature and a dream she had about him hurting her.
Even though they still remained friends, Bruce still had feelings for her. Later, Betty worked with Bruce on a device that involved gamma radiation and Nano-Med technology, that would be capable of changing the world of medicine using a Gamma Sphere.
When one of their colleagues accidentally armed the Gamma Sphere while it was still open, Bruce saved him and protected everyone in the lab from the blast by putting himself in front of it.
Miraculously, Bruce had survived. Then, Betty soon visited him in the hospital and expressed her concern over his condition, but Bruce told her that he was alright.
Later, Bruce began to transform into the creature known as the Hulk whenever he became angry. It was soon revealed that Bruce's father was involved in him changing into the Hulk because of the accident & radiation passed down from Bruce's father altered Bruce's DNA.
Once the truth was revealed Bruce's father retaliated against Betty's interference by sending mutant dogs to kill her. Angered, Bruce turned into the Hulk and raced to save Betty's home to fight off the dogs.
Successfully defeating the dogs, Bruce changed back. However, out of fear, Betty called her father General Ross in hopes that he and the military could help him.
Later, she learns everything about Bruce's past through her father General Ross and why Bruce was so repressed his whole life. She tries convincing her father to help Bruce with his memories and find a cure.
Contained by the military Hulk emerged again and broke out of the base. At the same time, Betty confronted Bruce's father who had also acquired of his own. Both of them transformed after a confrontation which escalated into a massive brawl between them out in the New Mexico desert saving everyone in the process as the Hulk.
Then, General Ross was forced to seemingly destroy them both with a special missile. But in reality Bruce managed to survive after that he secretly into hiding and flees the country.
Assuming that Bruce was dead, Betty continued her life. Betty's father and the rest of the army keep watch over her in case Bruce returns to her during a phone conversation with her father she tells him that she's not mad and wherever Bruce is, she's the last person that she wants him to find.
Because as much as she misses him at the same time, she's still in love with him, and wouldn't want to complicate his life any further.