Jungkook's hatred towards Jimin was only because he wanted to divert his mind from not getting what he wanted in life, the way he always wanted it. Jungkook was bad at feelings, he never knew when to shut up and when to show that he actually cared, even if he was a good person at heart.
Soon enough they did develop a friendly general atmosphere at home. Jungkook found himself smiling most of the time thinking of Jimin and his cuteness but never wanted to admit it because there would always be something that caused him to frown, for example his parents always saying things like 'I knew Jimin was perfect for you. He takes such good care of you. I knew you would never survive being alone'
Jungkook was a stubborn, egotistical and a prideful guy - when he first met Jimin after the proposal came along, he didn't wanna admit that the guy his parents brought along was indeed one of the most gorgeous men he has ever seen. He always wanted to find someone by himself, get to know them and then marry them, he never wanted an arranged marriage and just that thought made him dislike Jimin for no fault of the smaller