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.

Kim Soo Hyun's agency has finally addressed the rumours about his relationship with late Korean actress Kim Sae-ron.After the death of the High School Love On star’s in February, some pictures and letters surfaced on the internet

According to Goldmedalist – an agency established by Kim Soo-hyun and his cousin – the actors dated from the summer of 2019, after she became an adult, to the autumn of 2020. Kim Sae-ron was born in July 2000, while Kim Soo-hyun was born in February 1988.