For Yeung Hong, Gwok Jing represented a major obstacle to his plans. Gwok Jing was bent on killing Yeung Hong's adopted father, Prince Yeun Nan Hung Lit of the Jin Empire, as well as destroying the Jin Empire that was the source of Yeung Hong's wealth and power. For survival purposes, therefore, Yeung Hong was driven to destroy Gwok Jing.

That said, was it ever personal for Yeung Hong? I never got the sense that Yeung Hong actually hated Gwok Jing. Yeung Hong needed to get rid of Gwok Jing for his own self-interests, but if Gwok Jing had simply retired and disappeared, I have a feeling that Yeung Hong would not have bothered to pursue him because he had no personal enmity towards Gwok Jing.