Hope
He can't believe that she was really dead. Yes, the other one told him. But what can you expect; she was a Replicator after all. Why should he trust her? Just because the other one told him didn't mean it really was true.
He wouldn't give up on her. Not after everything he'd seen. But he just couldn't. And so he wouldn't.
But now that the whole expedition had been given the news, he had to pack her stuff. It wasn't really fair to them to be constantly reminded when they wanted to start the mourning. And so he removed her things from her quarters.
But on inside he knew that he wouldn't give up on her. Not until he'd seen definite proof of her death. He would keep looking for her. And he would not give up that flicker of hope he carried in his heart. He would keep the hope to see her once again. It was the only thing he was able to cause he still had things to do and say to her which he never had. And he hoped he would get that chance.