Shameless, gratuitous fluff. Set it whenever during their lives together you want.
I own nothing.
He could always tell when she'd had a particularly lousy day at work.
She'd grown to start sending him home at six or so, if she wasn't going anywhere in the near future – telling him to go write, or make dinner, or just something to get him out because the case clearly wasn't moving. So he'd say goodnight to everyone, sneak a kiss goodbye if he could, and quietly do as she had said.
He would usually stay up to wait for her, but occasionally, she'd text just to say, "Don't wait up". He'd then be in bed, with either a book or a notepad, by the time she collapsed through the front door. And he would wait until she was in bed, kiss her goodnight, and turn off the light – she'd often be nearly asleep by the time he settled down.
And he'd know that she had had an awful or a harrowing day when he woke up to her clinging to him. Sound asleep, her head on his shoulder and her breath against his neck, an arm around his chest and their legs tangled together. She was very rarely so clingy.
When he woke up with her wrapped around him, he could never bring himself to move.