Criminal Psychology

One day, while Lin Chen read a book, Xing Cong Lian said to him, “You’re a psychologist. Can you help me find out what kind of person is suitable for me to marry?”
Lin Chen remembered telling him love was the most immeasurable thing in the world. Even psychologists couldn’t predict love, because its progress in two people’s lives had countless variables.
What variables?
Lin Chen thought, at the time, the first variable was: You’re just an ordinary police officer who liked eating crayfish at the stall with a bottle of beer. I didn’t know you were…
Or: I didn’t know when I fell in love with you or when you fell in love with me.