Jungkook is a character who only experiences love within his fantasies, conceiving an alternate universe. He is undergoing a form of schizophrenia which produces a fantasy life to feel a fondness for a non-existent person, Kim Taehyung.
These fantasies and assumptions are slowly found to be untrue and are contradicted by actual behavior once an actual relationship forms.
He struggled with his insecurities and attempted to find ways to fit in. Though with his sinister past, he tells himself, he will nevermore have an happy ending. He conjures up this ideal 'friend', Kim Taehyung. Over the years, he gradually begins to fall in love since it was his only way to perceive love.
He strived to determine ways, in order, to be with him eternally. Though, he discerns it was entirely just a universe composed in his head. It just was all FAKE LOVE.
-
"We fall in love when our imagination projects non-existent perfection upon another person. One day, the fantasy evaporates, and with it, love dies."
- Jose Ortega y Gasset