People always understand the value of someone when they lost that particular person and gon was the same too. He never understood how much he needed Killua but when he realized it was too late, it was time to left each other. gon promised something that " Wherever we go we will always be friends ". when they finally aparted, their life became hard for each other. They find out they have some feelings for each other but it's was very late. will they ever meet each other.