It's not JUST that part (like I said in the post you initially replied to actually), that's just a point that stands out. Her whole argument for the entire bedroom section is flimsy and sounds more like she's trying to convince herself than she actually believes anything she says. But even then, the dialogue options you have are frustratingly bad when you get to reply. I immediately thought of MULTIPLE major flaws in all of her points, and the fact that even the good arguments you get just result in the main character horribly fumbling them is cringeworthy at best.
Also for the "I'm 14 and this is deep" bit, how about her entire spiel about "I am that mirror" when she gets into that part? It legit threw me out of the scene because it doesn't fit at all and really does just sound like a teenager's first edgy OC. Which is really rather a shame because like I said, up til that scene I really liked the character. It's a fun concept and I love to see it, but as I put it earlier, that conversation retroactively ruins everything that made her interesting.
And uh, no offense meant, but I'd really rather talk with the dev than with you. It's not really constructive feedback if we turn this into a petty back and forth disagreement like this.