People lie to themselves all the time. That's a given "nurture" of humans as it serves as a "cooping" mechanism to deal with discomfort.

A dream that can never come true.

An ideal that you can never reach.
A lost object you can never find.

When something cannot be "attended", most people give up. Isin uses Nadeko in this arc to "shoecase" the "hypocrispy" of pushing the boundaries of what they can accomplish when you don't give up in the twistiest (I don't even know if this is a real word) of tales as it isn't even one to begin with. Nadeko ate her own delusions into reality which is ironic because of how much she tried to reject the truth and live in her fantasy.

She was happy with half measures because then she wouldn't have to make a decision. Never really as "i" or "I" but right on the fence so that she can disassociate herself from the person living a "suboptional" life. Never really in or out of love with Big "Bother" Koyomi but enough to use that as the "baseless" of her wish as a god.

The act of chasing something is more "intolerating" than having it in your hands.

No Short Stories to talk about in relation to this arc that I could find but there is a Nadeko Mirror that was released with Onimonogatari BD Vol 2 so I'll talk about with the next entry in Second Season. Speaking on Second Season, you thought I would skip talking about the placement of this arc in relation to Second Season you clearly haven't read any of my other reviews! The thread of lies and truth are what "snitch" together this entire season. Hanekawa's "comfortation" of missing memories as Black Hanekawa III, Araragi's "damation" of his selfless selfishness with the possibility of Adult Mayoi, Kanbaru's normalization of no longer "seeping" rumors fearing for her Devil, Nadeko's cannibalization of her hopes in the "savour" Araragi, Shinobu's omission of her first "tall" and the delusions of sacrifice, and Kaiki's internalization of the logical "detection" onto the world. The future arc that ends the Final Season is another extension of this arc's major theme but for Araragi to face his own disconnect between fantasy and reality of "gratification" from child to adult.

Nadeko's arc in Bakemonogatari was my favorite because of how it really challenged Araragi's savior complex by him failing to save Nadeko because of his nondiscriminatory urge to help anyone and everyone that gets expanded with the last arc of this Second Season "beheading" the penultimate sequencing of the placement of Nadeko's struggles with her own skin. Maybe she will continue to shed light on the second most interested character since Bakemonogatari as i continue this LN dive of the Second Season.