I also dislike FL's personality, but her background shaped her personality. Her mother abandoned her, her aunt gaslighting her, her aunt's brother harrassing her, her high school classmates slandering her, her teachers doubted her, her college roommate dislike her (because she's sleepwalking often), her maternal? uncle and cousin ignored her, her younger stepsister hated her, her stepfather didn't want her. Only her late father, her best friends and her boyfriend love her.
So imo she had abandonment issue, trust issue, low esteem, mood swing, anxiety (which caused her sleepwalk), ptsd, depression, and panic attack (which caused her to runaway).
She wanted to stay away from his aunt's younger brother so she left the town to go to Yihe. Later she wanted to protect her boyfriend from that man's harrassment so she left the town again to Hongkong. I heard the novelist created ML based on love language: acts of service, so she's the perfect FL in the novelist's mind to highlight that love language.