A study of Hairu’s body comes back after the Rose Operation and it turns out she was pregnant with Ui’s baby when she died

Well I’m dead and you have killed me. 

“Are you sure?” Arima’s skin is almost green. Hirako sticks close to his boss as the autopsy doctor walks away. 

“What is wrong?” Ui stumbles up to them, his eyes bloodshot from crying. Hairu is dead.

Just last night they were giggling together under the covers in his apartment. He broke his ethics just to be with her. And he’d been planning on proposing soon – well, just as soon as he told Arima.

And now that future is ruined. That fucking ghoul removed her head, as if she were a toy and not a beautiful, brilliant, witty person.

Arima glares at him.

“No wonder Hairu slipped up. She wasn’t at her full capacity,” Hirako says quietly.

“What do you mean?” Ui cries.

Arima briefly fantasizes about punching Ui. “Did you know?”

“Know what?” Ui looks panicked.

“Ihei was pregnant,” Hirako says tightly.

Ui’s world spins. He slumps to his knees.

“You were the father, weren’t you,” Arima says quietly. “I should have paid more attention.”

“I didn’t know!” Ui wipes his eyes. No, no, no. “I should have stopped her. I – I did this to her!”

Hirako bends down to lift Ui up. “Hold on to me.”

“Let’s go into my office,” Arima says. “I’m not upset with you, Ui. Just surprised.”

“I loved her,” Ui cries. “I did.”

“I’m glad,” Arima tells him. Hairu was happy when she died, he is sure of it. Because all she ever wanted was to be loved.