Harry is just waiting to die most days. He puts up a good fake front but he doesn't take joy in much of anything really. He has moments of lightless, of happiness, but he's really only going through the motions. Ginny's given up on him being truly happy and has found her own contentedness in the midst of her husband's depression. In his darkest moments Harry can be almost like a human dementor, sucking the life and joy out of everyone and everything around him, and when that happens it's Hermione he goes to in order to spare his family seeing him that way. She doesn't mind. Her cupboard under the stairs is slightly larger than the one he grew up in, and if it brings him some perverse comfort to huddle in, who is she to judge? She's got her own coping mechanisms that aren't any healthier really. At least his are solo pursuits.