This article kind of summaries China & South Korean relations for the last 30 years.
The only difference now is that China is no longer in the rear view mirror for Korea, it may be the other around. Seeing that, that makes the Koreans a little more uptight.
Just give them space, and leave them alone. They will not be going anywhere or doing anything too drastic. They will calm down and come to their senses eventually.
the article does bring up a few main events in sino South Korean relations. Although it didn't go back far enough and missed out plenty of controversies.
South Korea government actually one of few last remaining one in the world that switched recognition of china from ROC to PRC. Even after their US overlord did it, they still stuck on Taiwan government for a longer time.
Since then sino south Korean relations did improve even went on a high during the time widespread anti American sentiments in SK after some US military scandals involving deaths of SK civilians by US military personnel. However it also had many bumps exacerbated by South Korean nationalists involving the Goguryeo issue, Mt Changbai, UNESCO etc. All under shadow of SK as US puppet.
I agree with the idea they will eventually get used to China leading position in North east asia. It will be struggle for them though. They hate to be reminded of their status as one of China vassal state in imperial times. The cultural links between two nations. Also they have developed a sense of superiority during the times they got far richer than PRC and DPRK. You can see this in their haughty attitude towards the ethnic Chinese, the ethnic Koreans from China or Chao Xian Zu, and the north Koreans that live and work in SK. It's despicable.