SEOUL, March 29 — Accused of “betraying” fans, subject to relentless online and real-world public abuse, K-pop star Karina recently issued a grovelling, handwritten apology. Her crime? Dating a South Korean actor.

Her plight mirrors that of many K-pop stars before her, experts say, such as late singer Sulli, who have bemoaned strict behavioural controls and being held to impossibly high standards, as record companies seek to sell fans the perfect idol.