Opening the door to let them both in, Ron dropped the bags of things he'd bought on the ground by his shoes, which he also removed and shut the door behind Hermione, grasping his wand and whispering a spell to turn the lights in his flat on as it was starting to get dark out.
"Hermione, any night can be a night you stay over. I don't care if I have to be half way across the world at 6 am the next morning." He grinned at her before making his way into the kitchen to look in the icebox and see if he had all the things needed for their planned Italian dinner.