Granger had apparently decided that her flat was inadequate in comparison to the manor (or perhaps it was simply that Draco was at the manor and not at her flat), and she began staying the night every time. He had to try quite hard indeed not to die from arrogance whenever he arrived at the Ministry with her in the morning or stepped into the fireplace at the end of the day, declaring "Malfoy Manor", as Granger stepped in with him.