She was kissing him again. She did that a lot, and it made the Doctor uneasy. But this time it seemed different - she seemed almost... desperate in her advances, rather than her usual cheerfully-flirtatious self. He grabbed her hands and eased her gently away so he could look at her face. Then she shocked him. Her face crumpled... and she began to cry. He was aghast, and when she pulled away from his grip on her wrists, he let her go without a struggle and stared at her as she turned away from him, tears trickling down her cheeks.
He reached out, but didn't touch her. River was crying. River was crying. He'd seen many many humans cry, and he was never comfortable with it, but this was River Song, silently weeping just past the ends of his outstretched fingers. River never cried. He tried again, clearing his throat and taking a step forward to touch her shoulder. "River?" She shook her head, and he let his hand fall, trying hard not to flap it ineffectually as he tended to do when she flustered him. Which happened a lot. He sighed. "River. Please tell me; what is it? This... all this... it's not like you to do this. Please... River, please tell me. I can't stand to see you like this - I can't stand to see you cry - not you. River." She had stopped crying, and she was listening, but she looked... she looked so sad. This time she let him take her shoulder and turn her gently toward him so he could enfold her in a hug. They stood there, swaying a bit, as the tension in her muscles faded, bit by bit, until she finally let out a great sigh and nestled her head against his shoulder. He sat down, still embracing her.
"Can you tell me? What can I do to help you, River?"
"I don't think I can tell you. Spoliers." Her voice sounded rusty from all the tears, but there was a tiny smile in it at the last word.
"Well then, let's see if I can guess," he mused, counting off on his fingers. "Hmm... pandori... no that's done and what about the cracks in the... no that's done as well. Weeping Ang-" he broke off mid-word as she looked up sharply and put a hand over his mouth to stop him. He kissed her fingertips and stroked the captured hand as he continued. "Right, now we know that you and I are married in my future, your past, and that... oh. Oh." He brought the hand back to his lips and kissed the fingertips one at a time, lingeringly, as he thought aloud. "Now, it follows that my first time with you is your last with me and..." He broke off again as her eyes filled with tears once more. He released her hand and used his own to gently wipe the tears from her face, understanding now.
"River, you know I don't - er - love my Companions that way. They're all lovely people, well, except for him and well, she wasn't at the beginning but by the time she saved the universe..." he trailed off, looking sad himself. It made her ache with sympathy for him. He had lost so much. She took his hand herself this time, bringing it to her lips and sucking lightly on each fingertip in turn. He shook his head, visibly taking hold of himself, and smiled at her, before closing his eyes briefly to enjoy the sensations of her sucking his fingers. "At any rate, lovely people, yes, and you're a lovely person and-" he broke off again as she bit him lightly.
"I'm not a lovely person, Doctor".
"You are, oh you are, so much, but you're not only a lovely person, that's what I'm saying. River, you've piloted my TARDIS. You know my name. No-one else has ever - ever - done those things. You are not merely a lovely person, River, you are not just a Time Lord's Companion. You are River Song, beautiful and crazy and amazing and complicated and strange and lovely River Song. Now," and this time he kissed her, putting all the passion and confusion and affection and fear and yes, love into the kiss as he could.
"You know my name, River. Say it. Say my name."
She whispered it, murmured it, moaned it into his mouth as he kissed her.
And as for the rest... spoilers!