In the ninth episode of Japanese drama, Li said to Jian, "You have been together for so long, and you really don't understand anything." What does this mean?

It shows that Kenzo didn't understand Li's mind for a long time. That episode could actually change Li's mind, but Kenzo didn't express it in the right way. In fact, Li has always liked him since elementary school and has a good impression on him, but Kenzo didn't notice it. In that episode, Li really wanted to say three words, that is, "I love you", which was enough to make her change her mind, but Kenzo didn't say it until the last episode.