Jungkook was your boyfriend.
You guys had broken up because something had caused you to feel nothing. Just numbness. You weren't the same girl that had boldly taken his heart at first sight.
The relationship was perfect, until he looked closer at it. But he still couldn't not admit he loved you still. He didn't want it to be over. He just wanted you back. He tried to move you out, but you wouldn't. It made him more frustrated about it.
He pretended that you cheated. He pretended that you had broken his heart, and the breakup was necessary. He needed to hate you. Even if it hurt. Even if he had to lie to himself.
But nothing. Worked.
So one day, stubbornly you still in his apartment, he came up to you and looked you in the eyes and said, "I hate you." His tone was cold. He was trying to convince himself. But he ended up convincing you instead.