A month ago, Hee-won, who found out that Min-wook and Miran were dating a friend and decided to spend one night with a stranger due to the shock, will get pregnant with Doo-joon, whom she met in Time. He is reunited with his student, Sehyun's uncle, Dujun, at a hospital he visited with Miran and finds out he is the president of Daehan High School.
Hee-won's slip of the tongue turns out to be Du-jun's child, and Du-jun asks for marriage, but Hee-won refuses. Rumors spread that Hee-won was pregnant at school under Ji-hoon's ruse while continuing her mandatory date with responsibility for the two lines. After hearing from Sehyun, Doo-joon makes a bombshell announcement that he will get married in April, and Hee-won is forced to follow the decision.
Hae-in, who appeared at Du-jun's wedding, trespasses on their officetel without permission, and surprised Hee-won runs out of the house after a sudden morning sickness. Du-joon visits Hee-won and realizes his earnest feelings about her. Meanwhile, Hee-won attends the Korea High School athletic meet and confesses to Doo-joon, who works hard to help out and comforts her feelings of betrayal to her mother.
After confessing their love to each other, during their happy days, they have a quarrel over their school trip, and during their brief separation, they realize the urgency of each other and become stronger. However, Doo-joon, who finds a Hae-jin who escaped a mental hospital trying to storm Hee-won, who is leaving the office in a car, flies to save her, and Hee-won loses her mind.
Hee-won, who woke up from the hospital, hears Du-jun, who is injured but only cares about her safety, and realizes that the idea that she might be loved by two strings is wrong. Hae-in is eventually arrested, and Doo-joon and Hee-won confirm their deep love for each other, which puts priority over responsibility.