She knew too much. Her body shook with the knowledge. Her mind ran away from her. She couldn't handle knowing; she couldn't bear the blame.
Kana-- his sweet Kana --knew too much, saw too much. Akito made sure she regretted it; Hatori made sure she forgot it.
Her eyes were unfocused, her whole conscious burdened with their secret.
Hatori buried her memories easily. He hated himself for it, but he hated himself more for making such memories with her to create guilt and blame that she couldn't cope.
He split between happiness and regret when she married someone else.