In MBC's Friday-Saturday drama "21st Century Great Lady," Byun Woo-seok and IU announced the beginning of a romance. In episode 3, which aired on the 17th, Seong Hee-joo (IU) and Prince Ian (Byun Woo-seok) grew closer through a contract marriage. After the scandal, the two held hands as if acknowledging their relationship and entered the palace. Queen Dowager Yoon Yi-rang (Gong Seung-yeon) opposed the marriage but decided to proceed as planned.

When a photo of Prince Ian kissing Seong Hee-joo late at night was published, he stated, "I can no longer delay making a statement." Prime Minister Min (No Sang-hyun) advised, "Admit it to manage the situation, but firmly deny the possibility of marriage." Yoon Sung-won (Jo Jae-yoon) suggested that since Seong Hee-joo was a commoner and illegitimate, it would be better to send her away from the residence, but Prince Ian replied, "She may leave easily, but she could also become my wife in the future." He added, "Many people already live in my residence—retainers, guards, even cats. Adding one more woman won't change anything," protecting Seong Hee-joo.

Seong Hee-joo suffered from malicious comments and egg attacks due to dating rumors, and her father Seong Hyun-guk (Jo Seung-yeon) also showed a cold reaction. Prince Ian comforted her by bringing her to his residence for protection. When Queen Dowager Yoon Yi-rang accused Seong Hee-joo of being responsible for the fire accident at Tanilyeon and tried to expel her, Prince Ian confronted her directly. Palace officials who witnessed this scene whispered about their relationship, and Yoon Yi-rang's plan failed.

The broadcast also showed a scene where the two fought over a blanket on a bed, causing misunderstanding among the palace officials. Another scene depicted Seong Hee-joo preparing tea and nutritional supplements for Prince Ian, who was working late into the night. Prince Ian gently caressed Seong Hee-joo's cheek and kissed her carefully. This scene recorded a peak viewership rating of 12.7% (according to Nielsen Korea). Episode 3 achieved ratings of 9.4% in the metropolitan area, 9% nationwide, and 4.6% in the 20-54 age demographic, ranking first among all programs aired on Friday. The drama maintained its number one position in the Friday-Saturday drama slot and its time slot, achieving a triple crown.

Meanwhile, in episode 4, Seong Hee-joo nearly had an accident while driving a car with faulty brakes, but Prince Ian stopped the car and saved her. Prince Ian was injured, and Seong Hee-joo showed a shocked expression. The royal family prepared an official statement recognizing their relationship, which enraged Queen Dowager Yoon Yi-rang. The queen dowager advised Prince Ian to attend a dinner with palace reporters accompanied by a woman she chose, but Prince Ian refused.