He wakes up feeling the soft caress of her lips on his cheek, only to open his eyes to an empty room, first light making its way in through the window, his heart fluttering in his chest. The woman.
He has no cases today (my kingdom for a good murder!) and she won't leave his head. It makes him feel weak, not in control, and he takes it out on John with scathing remarks and restless irritability, until he's driven him from the flat ("I'm going OUT. Don't call or text me or I will invite your brother over for tea.").
He watches through the window as John disappears down the sidewalk, then picks up his violin and begins playing her theme, which he'd composed when she'd falsified her own death (We have that in common, don't we?). He doesn't permit himself to think about where she might be or what misbehavior she might be getting up to, just allows the rolling, exotic melody to fill the yearning emptiness inside.
A good murder really would do right now.