Even though Gu Xiaonuan knows these things, she ultimately cannot agree to them.
Gu Xiaonuan knows when to say and do what, so when Li Lu's attitude towards Si Yuchen became unusual, Gu Xiaonuan had already decided not to listen to her opinions any longer.
Gu Xiaonuan can't explain it, after all, Li Lu keeps saying it's for her own good.
But in Gu Xiaonuan's eyes, as long as her life is entangled with Si Yuchen, there will be no good outcome.
Gu Xiaonuan might still think it's her own problem, but later she realized that no matter whose problem it is, it always ends the same way.
Li Lu's attitude towards Si Yuchen is just different, and it's not something Gu Xiaonuan can persuade Li Lu about in a few words.
Just like Li Lu can't be persuaded by Gu Xiaonuan in a few words either.
Gu Xiaonuan's temperament is similar to Li Lu's, neither of them will be swayed by the other's reasoning.