It's what came to mind first to me too, but it's important to realize that you can't easily go by a translation's exact wordings as foreshadowing.The "You'll never understand" is foreshadowing Eito becoming a girl, right? Like, I know that I'm a bit biased here, but surely that's how everyone else is reading that, right?
Uesugi: I am the one who says gexGetting your fellow guy friend to call you cute.. to what end, Uesugi?
Or it's a fake-out and she is blushing because she has a fetish for guys turning into girls and suffering with menstruationOoooh. Glasses girl wants some of that Eito action, eh? 🤔
No its because uesugi is becoming more of a girl in her heart. She can't talk about things like menstruation with him. Because it's a girl subject. This is just showing how their dynamic is changing from best guy friends to guy and potential girlfriendThe "You'll never understand" is foreshadowing Eito becoming a girl, right? Like, I know that I'm a bit biased here, but surely that's how everyone else is reading that, right?
Also, Noel really should have realized that Uesugi wasn't going to get that reference. And even if he did, how would he know that that's what she meant by it? She can't really consider that a confession, can she?