It turns out that the rumor Jungkook BTS is dating is from here

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Big Hit Music also responded to the dating rumors of BTS member Jungkook, and the source of the rumors turned out to be the Youtuber himself whom V personally warned to sue.
After actress Lee Yoo Bi's management company responded to the dating rumors with Jungkook on December 27, Big Hit Music also denied the dating rumors of Jungkook.
In fact, the original dating rumor was from a YouTube video by the YouTuber himself that V himself announced he would sue about a week ago.
Specifically, on December 23, this YouTuber posted a video on his channel claiming Jungkook and Lee Yoo Bi were dating with "evidence" that he collected online.
This is not the first time this person has spread dating rumors of BTS members.
In November, he claimed that Lovelyz's Jimin and Jeong Ye In were dating as well as confirmed that V was in a relationship with Chaebeol's daughter.
Meanwhile, Big Hit Music said it is taking action against posts that "cross the reasonable and acceptable boundaries of personal expression and commentary".
It also said the company regularly monitors social networks and online forums with posts about their artists containing "deliberate criticism, baseless disinformation, and attacks." individual".