Thor takes a breath at that. Some small part of him wish he hadn't heard it, but he knows that there's no running from it. The truth of the matter is that Gamora might well still live, but it was equally (or more) likely she was dead. The only thing that perhaps saved her from death was that she was Thanos' daughter, but if Thanos' snap had eliminated without discrimination, she could just as well be dead.

"Good night," Thor tells him as he stands, though he's sure that Quill doesn't hear him. Thor lets himself out, shutting the door behind him.