Uzui had been bothering Genya with various things, especially with you. He had told her that you were going to leave him and Genya felt bad about that, it bothered him so much that he ended up believing her.

Uzui didn't know that he had believed her, she was just joking with him, but Genya took it VERY seriously that she went to look for you in your room with tears in her eyes

"You won't abandon me, will you?!"

Genya had a tears and was standing at the door of the room waiting for you to answer him.