I think somehow Kwon (uke) and Yooyeong (black hair one) fell in love with each other but Yooyeon didn't want to admit it. Then Yooyeon (white hair one) took over Yooyoung's (black hair one) body in his previous life and inflicted all the violence on Kwon (uke) because of his jealousy toward Yooyoung. That's why Kwon started to fear Yooyoung and distance himself from him in the past. But Kwon somehow found out about this replacement between Yooyoung and Yooyeon made by Yooyeon. So Yooyeon afraid Kwon will learn the truth again
I think somehow Kwon (uke) and Yooyeong (black hair one) fell in love with each other but Yooyeon didn't want to admit it. Then Yooyeon (white hair one) took over Yooyoung's (black hair one) body in his previous life and inflicted all the violence on Kwon (uke) because of his jealousy toward Yooyoung. That's why Kwon started to fear Yooyoung and distance himself from him in the past. But Kwon somehow found out about this replacement between Yooyoung and Yooyeon made by Yooyeon. So Yooyeon afraid Kwon will learn the truth again