Gu Xiaonuan doesn't know anything right now, but that doesn't mean she doesn't understand what's happening. She doesn't yet know the relationship between Lu Xiao and Gu Qingyuan, but sooner or later, she'll find out their secret.
Gu Qingyuan and Lu Xiao teaming up is definitely the most surprising thing for Gu Xiaonuan.
In such a situation, there's really no need to think too much, after all, these issues don't require her excessive doubts.
If she thinks too much, then why would she trust Si Yuchen and leave everything about Gu Qingyuan and Lu Xiao to him?
Si Yuchen has her trust, so he should do things that make him trustworthy, and that is why Gu Xiaonuan won't overthink it, regardless of whether others really have such thoughts.
Si Yuchen doesn't want to think this way, but he is also someone Gu Xiaonuan trusts.
Gu Xiaonuan trusts Si Yuchen, so even if Si Yuchen hasn't accomplished other things, he still won't say much.
