Kang Daniel's advisers must have told him he cannot "betray" his fans, especially when he has just started to forge a solo career.
The former member of boyband Wanna One is dating Jihyo of popular girl group Twice, with the news leaked by media outlet Dispatch.
It also published photographs of Jihyo turning up at his home in a Mercedes and wearing a surgical mask.
In a competitive Korean entertainment industry where fans retain a fantasy of "owning" their idols, the revelation has upset some.
One posted online that it was stupid of fans to worry over Kang's recent battle with a previous agency over control of his career while he was having a good time romancing Jihyo, 22.
Their relationship reportedly started from late last year.
Kang, in an effort to repair the damage, has now issued an apology for not personally telling his fans about his love life.
"I'm sorry I couldn't reveal this earlier, and I am sorry to have to release the news in this manner," the 22-year-old posted.
Thanking the fans for what they had done to keep his morale up in his times of doubt, he promised to repay their faith in him by morphing into an artist who is "better than the one he is today".
But even as he tried to curry favour again, some fans are not happy his agency is trying to silence naysayers with threats of legal action.
Meanwhile, the representatives for Twice singer Momo and Super Junior's Kim Hee-chul have refuted talk they are dating, with pundits speculating over whether the hoo-ha concerning Kang's romance has frightened them off.