
Why are they not changing eye colors anymore? Isnt that the main detail of the story? Why is the author forgetting to change it in crucial moments

Being emotionally stable doesn't mean not crying, it means being able to properly express their true emotions. Because b4 when she was as slave, she did not have the luxury to feel sad or be happy so she suppressed her feelings and her eyes changing was the only indicator of her true feelings. But now, she is able to be true to her feelings that if she's smiling, she's really actually happy, so ig there's no need for her eyes to change rn because she no longer needs to hide her emotions...
It could be this or the author just doesn't want to change them anymore, idk these are just my uptake from the progress of the story.

I understand what you mean but the main point of the story is that their eyes are a reflection of their emotions so if she's happy they'd be gold and when she was anxious they were green which was shown earlier in the series but now it seems that the changes have altogether stopped for her. The last eye color change seen was the 3rd bro Ezra(or Erza idk which one).
Also since she's finally becoming in tune with her emotions the changes in eye color should be more frequent since she's experiencing things she hadn't before, compared to the brothers who have more control over their emotions.
I knew it. I called it since like, chapter 5!! When I knew the targets all had Louis' description, I immediately knew its the duke!! And his obsession to Louis!! Fuck that