Lee and Byun have been dating since 2012. The couple is expecting a baby this spring.
Lee’s mother, Lee Ae-ja, said the baby is a girl.
“I’m really happy that they are having a baby,” she said. “Yong-dae told me he wants to raise his daughter to become a badminton player.”
Lee announced his national team retirement last year after he and his partner Yoo Yeon-seong got eliminated in the men’s doubles quarterfinals at the Rio de Janeiro Olympics.
The 28-year-old is currently focusing on playing in professional badminton leagues in Southeast Asian countries.