thanks for reading.
The reason for her suicide attempt was that she had been threatened with obscene images, which destroyed her mental health. She had been spoiled by those around her and her mental health was very fragile, so she could not take it anymore and committed suicide.
Yuu Ashinaga is a classmate of the protagonist. She threatened Suzuka because she was jealous of Suzuka's popularity in her class. However, there is a collaborator behind the scenes. You will find out in the next story.