What episode did Lin Beixing discover about his best friend?

Lin Beixing found out in the plot of episode 1 that her best friend was her fiance's new girlfriend.

In the plot, Lin Beixing, who is about to marry her boyfriend Yu Zhan for many years, is divorced by her boyfriend, and Lin Beixing comes to the seaside for a drink. Grandpa, who was chanting for bait, gave her his fishing rod and told Lin Beixing that the whole world was behind her, in her past. But just looking back, grandpa was gone. Lin Beixing had to go home with fishing gear. Faced with her mother's nagging about wedding planning, she was too sad to speak. She didn't have the courage to tell her parents that the wedding nearby was cancelled. After turning out the high school uniform, Lin Beixing decided to make a final effort. As long as Yu Zhan shows up at the campus to take wedding photos on time tomorrow, she will pretend that nothing happened.

Later, Lin Beixing unexpectedly went back to the past and found a boy Zhang Wansen who opened an umbrella for her. Yu Zhan later asked her to take something back. Standing at the seaside, Lin Beixing received the urging from her mother, the director's dismissal call and the news that Yu Zhan would introduce a new girlfriend tonight. She stood at the gate of the hotel waiting for Fujita, who has been abroad for many years, and this good girlfriend is Yu Zhan's new girlfriend. Lin Beixing was extremely angry and smiled. She really didn't know what words to use to describe the present situation. Wearing a wedding dress, Lin's mother happily took pictures, but Lin Beixing shouted not to get married. How can the groom get married if he doesn't love himself? Holding a skirt, Lin Beixing wandered around the street blankly. After drinking ten cups of milk tea, Lin Beixing decided to let go of the past. Lying in bed, Fujita edited a commemorative video of high school and sent it to her, hoping to be forgiven.