Kim Soo Hyun and Kim Sae Ron were in a relationship. However, the former actor’s agency denied alleged involvement in Kim Sae Ron’s financial struggle and death.

Hoverlab, a South Korean news commentary site on YouTube, claimed that the actor and the late actress Kim Sae-ron had been in a six-year relationship since she was 15 years old.

Ron's mother countered the claims through Garosero Research Institute, made by Kim Soo-Hyun's agency Gold Medalist including the love letters sent to her daughter, which were described as being sent by a "close friend.