
God forbid she have emotions, was it cruel? Ofc but everyday for her is constant negativity because of fake bestie, she's paranoid she's tired she's just had enough so a moment of being cruel got him thinking "wow I'll make her happy by betraying her exactly as she feared and being king and we'll be happy again when i shut everyone up!" Real thinker he is
Tldr: one bad moment shouldn't define her after years of hurt

we have no perspective from him. And one bad moment is sufficient to ruin a lot of what you work for in a relationship. I get that she was having a bad moment and feeling negative, she could've screamed, yelled, cried, said "you don't understand the things you're talking about", but it is a very below the belt thing to do to attack him personally for his status. Cruelly cutting him down is not the way. And if you do it, apologize IMMEDIATELY. She didn't. She just sees him betraying her by going for the ogFL.
That is not acceptable behaviour due to a bad moment. It was also low of him to go for the bestie who torments the FL, but i see that as him being just as cruel to her as she was to him. It doesn't justify years of him being with, and then eventually marrying the ogFL. But like I said, he is aiming to oust the crown prince, just as she suggested in her anger. All i'm saying is she is just as much at fault for their relationship falling apart.

She's cruel??? For just stating that they're both powerless against the rumors?
All she said was that they both can't change anything because they're extras.
You're acting like she broke up with him, abandoned him, and married their best friend/enemy with no explanation-- oh wait, that was him who did that, wasn't it? Who's the cruel one here?
I don't care if the ex-bf has an explanation, or that he did all this so they could be together. Leaving her like that with no communication and getting together with the girl who was making her life miserable is much crueler than what FL just told him.
Like, in real life, if your bf/gf just said that "we can't do anything about the rumors because we're just average middle class citizens, if you were president maybe you could do something" you'd find that crueler than them breaking up with you and marrying the person you hate the most!???

lol, this is just a different perspective i guess. Every one has a different standard of what would hurt them, and I think hearing FL's words from someone i do my best to support would do a number on me, so much so that I would feel a bit vindictive. To clarify, don't judge this moment by his later actions, coz i'm not saying he was right marry her nemesis. Take this moment in isolation. And from his perspective.
This girl that he's dating , who he encourages, was quite cruelly highlighting the lowliness of his position. She didn't say
"they won't listen to people like us, they'll only listen to someone as powerful as the emperor"
what she said was
"you're just a little viscount, who doesn't even have enough clout as I, a duke's daughter have. When you're lower than me, don't expect yourself to be heard. Maybe if you one day rise to be an emperor."
There's a massive difference in the meaning and implication here. She was cutting and taunting ("maybe someday if you're emperor they'll listen?" is clearly sarcastic).
If a teenage boy listens to that, and is massively hurt by that, what is he supposed to do? I know that i would wish to hurt back the person who hurt me in such an unprovoked and terrible way.
Now I don't know his motivation, like I said, we don't have his perspective. Is he doing this to actually rise to the position she asked him to? Or is it to hurt her by marrying the girl she hates? Or is it actually to torment the ogFL, making her do his dirty work for her, because he knows she's using some underhanded methods? Who knows? And maybe you still disagree with my take here. I think that the first person POV here is making us not evaluate the FL objectively, which is what it's supposed to do.
but that was very cruel of the FL. She sent the black hair dude down this path herself, and then thinks he betrayed her.