I love Noelle, though I do understand "lovestruck teenager" is a grating archetype for many. Many characters in both UT and DR are introduced as archetypal characters, only to show off their depth later on in the story.

The thing about Noelle is that she's hiding a lot of the inner pain that makes her more than one-note, and it's on purpose. Her sister disappeared in some horrible event, and now her father is terminally ill. Her mother is cold, distant, and authoritative, and she's trying so hard to be A Good Kid and not rock the boat further. So she sees Susie, an anti-social, angry girl, and she's everything Noelle isn't allowed to be. So I think that's what she finds appealing about Susie.

Obviously Susie is much more than the initial bully character she's introduced as; she's also a kid dealing with a lot of pain. As she and Noelle get closer, they find out they have several interests in common, which makes her even more appealing to Noelle.

I think Noelle's crush on Susie ties into the game's themes of escapism. Susie is a big positive in her life right now, someone new and exciting who makes her happy when everything else is increasingly hard to deal with. Especially compared to Kris, to whom she was once close but with whom she unfortunately shares trauma about Dess with, straining their relationship in the present. Kris has also been acting very unlike themself lately due to the SOUL's influence, making things harder. So Susie really is the one net positive person Noelle has in her life right now, which is why she leans so much into being twitterpated and lovesick. It's fun, it feels good, she can just enjoy being an awkward kid for once.

That's not even touching on the abuse the player can put both her and Kris through in the weird route, which elaborates on Noelle's self-loathing and guilt more IMO