It's only once they are going to bed, that River cries. He had dressed in TARDIS blue pajamas, and when he turns to the bed, River is already there, wearing one of his white button-up shirts, tears glistening in her eyes. The bed sinks slightly under their combined weight, and the Doctor sits next to her, covering her hand in both of his. He lifts it to his lips and kisses it gently.
She drops her head heavily on his shoulder, bawling silently into the fabric of his pajamas. He carefully bundles River into his arms and lies back, pulling her gently down with him. With a free hand, the Doctor grabs the blue duvet and tugs it up to cover the both of them, tucking it under her side. She grips his arm tightly, her back shaking as her body is racked with gulping sobs.
He stares at the top of her curly head, kissing her wan cheeks and forehead, rubbing her back in large, comforting circular motions. By the time River has cried all of her tears, the shoulder of his pajamas is soaked with salty tears. They lie there for several long, silent minutes, tear tracks drying on both of their faces. She helps him out of the shirt, tosses it over the side of the bed, and leans in to kiss him.
Later, after they make love, she drifts off to sleep; head on his bare chest, her wild curls spread out in a golden-brown halo around her peaceful face. After an hour or so of listening to the slow, easy in-and-out of River's breathing, the Doctor falls into an uneasy sleep, drifting in and out of dreamland.
When River wakes the next morning, he is already awake, watching her with a small smile as he fiddles absent-mindedly with a single curl. She drowsily smiles back, stretching in a catlike way, rubbing a hand over her slightly swollen eyes. They lie in bed for the morning, snuggled under the covers. And when the Doctor thinks she is dozing, that is when he whispers, "I'm sorry, River."
To which she replies, "you have nothing to be sorry for."