Alex picked a chair in the room and then sat on it. After learning about Alice's real plan, he changes his mind. Before, he wanted to stop it so Amu would send him out of the realm quickly, but now he had another idea.
"Don't worry, she is alive and well. If I wanted to use her life to threaten you, I would have already done it."
Alex took out his phone and then pressed a button to show Alice what happened inside the cube. "See, your sister is now cuddling with her lover."
Seeing this, Alice felt both relieved and angry. She was relieved her sister was alright but angry about her sister's current actions.
'No wonder she said she doesn't want to join the last phase of the mission.'
She then started suspecting Aurora's reasons for helping her. It's possible Aurora just wanted to be with that man.