Why did So-Hee Yoon get pregnant when she was black and glorious?

Have sex with a hero. Dark Glory is a fictional TV series, in which So-Hee Yoon is one of the characters. In the plot, So-Hee Yoon is pregnant because of having sex with the hero. The play tells a story set in a gangster, mainly telling the story of the gangster Lin Zihou and his men fighting for power and profit in the dark.