My best guess would be the preceding events before Hakuoro's transformation. I'm going to go with the game's depiction of the scene for the most part.
The game shows more happening to Kuuya mostly due to the fact that she's awake through the whole event, rather than lying there unconscious which the anime shows. She learns of Hien and Hauenkua's betrayal and their allegiance with Dii, causing her to attack them after Dii kills Genjimaru. What the anime doesn't show is that she's still in her Avu Kamuu during the time of the attack, rather than having it damaged beyond repair during her fight with Hakuoro. Also, she is attacked directly by Hauenkua and Dii (in his transformed state)
Before she sees what's left of Genji, Hakuoro, in his transformed state, tries to console her and make her calm down. However, seeing what Dii was at the time and Hakuoro directly mimicking his appearance, Kuuya screams at him to get away, thinking that he's the same one who attacked her. She tries to escape by falling out of the Avu Kamuu, but unfortunately ends up landing right next to the remains of Genji, finally realizing what happened.
To bring up the anime, Kuuya sees what happens to Genji, causing her to react the same way. While she does see Hakuoro fighting in his transformed state it isn't as overt as the game's depiction of the same scene and that she doesn't see most of it. I think the biggest impact on her was Genji being murdered right in front of her.
So, I think while Hakuoro may have had some hand at it, it was more of a combination of events. Hope this helps!