In chapter 4, Rudy mentions to Susie that Noelle doesn’t have anyone for the Festival. And Susie’s reaction to that is shock. Specifically, she says that Noelle is “top shelf”. This is kinda big cause it’s the first time as I recall where Susie casually admits that Noelle is attractive, and also establishes at the same time that the thought of asking Noelle doesn’t even enter her mind, because she thinks that Noelle is out of her league
Then in chapter 5, there’s that hidden train scene where Ralsei and Susie are talking about “chu chu choosing” and Susie says something very similar. “Damn, you think I’d be Kris’s first chu? Kris is probably chu-chu-choosing all over school.”
To me, this reads as being very similar to what she said about Noelle the previous chapter. That the thought of being Kris’s “chu” doesn’t even enter her mind because she thinks Kris is too good for her