First, her husband's attitude made her make this decision. As can be seen from the video, Su Min has not met her husband for two years. When she came home, it was not a warm greeting, but her husband's ridicule. Her husband said Su Min didn't want to go home if she couldn't get along. After coming back, her husband's attitude hasn't changed at all. Su Min still has to face all kinds of difficulties in life, which makes her decide to divorce and live her own life.
Second, she doesn't always want to live for others, but also wants to live for herself once. In the decades of living with her husband, their living expenses were AA, while Su Min's expenses for taking care of the family, the elderly and her husband were not AA, and only Su Min was responsible. Her husband never cared about her, and she didn't want to live like this anymore. Going to road trip helped her find herself and happiness, and she wanted to live for herself.
Third, an unhappy marriage can really make people depressed. Judging from her husband's attitude towards Su Min, her husband has no feelings for Su Min and has never considered Su Min's feelings. Such people brought misfortune to Su Min's marriage, and the unfortunate marriage made Su Min depressed and self-mutilated. She decided to divorce and prepare for a new life.