Jungkook's life wasn't so great. He never forgot about Yeeun. He never took his "dose". He didn't want to forget her. So he pretended to take it everyday. He pretended his feelings faded. He pretended that his memories of her faded. The first year after he returned with Eunji, she cheated on him. He kept asking her why. She then left him. She never came back.
Jungkook was looking throughout their house. Just to find his phone. But he found divorce papers. Eunji signed them, that really meant she wasn't coming back.
Jungkook was devastated. He lost the love of his life, for no reason. But he didn't lose his memory of her.
He later went and turned in the divorce papers. Finally, he would have nothing to do with Eunji.
Once they were declared divorced, Jungkook moved out of Sorato. He wanted to find Yeeun. He wanted to hold her again.
But she moved, she changed her number. All of his attempts to reach her failed. She was gone.
After those four years passed, Jungkook never stopped looking. So he got a job, he got a one bedroom apartment. He provided for himself those four years. He never gave up trying to find her.
He was an office worker. But to make a bit more money he worked in Uber eats.