This is a fluff story that goes with the 2015 Christmas Special "The Husbands of River Song" It may not make sense if you have not watched it.
The longer he was with her, the more he realized that it wasn’t an act. She really stole his TARDIS without him knowing? What was with all of these “husbands”, and did she mention wives? It was enough to make him sick.
That speech. How could she think that he didn’t love her? River could drive him mad sometimes. For a moment he had thought she had seen him with that face before, and was getting him back for who knows what? If the life of a time traveler wasn’t confusing enough, he tended to regenerate. He was also passed his “allowed” regeneration cycles. He supposed it was possible that she was saying most of that just to buy time until the meteor strike, but he had a feeling that what she was saying came from what she thought was the truth.
Now here he was looking out the door and looking at the Singing Towers with River at his side. He thought back three regenerations and two faces ago. She had told him where the last night they spent together was. Both of his hearts were breaking. He knew he couldn’t tell her. It was obvious that she had spontaneously saved his life in the library. He turned around as he heard her footsteps. She was happy. That’s all that mattered now. He knew it wasn’t his fault, but he still felt guilty.
She put her finger to his lips. “I know what you are going to say, so don’t.”
“Just listen. All I needed to do was touch you that night. I would have found one way to do that. I wouldn’t have gone through all of that, especially since we didn’t have a lot of…. time.” He was thinking of the right word. In all honesty, “time” wasn’t really it. Time was stuck with everything happening all at once just because she refused to kill him when she was supposed to. Women could be so stubborn sometimes! “I don’t just go around marrying people.”
“Didn’t we just have this discussion? Elizabeth I, Cleo— “
“Ok, I don’t just go around marrying people and then choose to spend time with them.” That made him sound horrible. He remembered the discussion they had when she pulled her diary out at the restaurant. Maybe he was, or maybe he was scared. He was the reason she died, after all. He knew it, but she didn’t. There was nothing that he could do now that didn’t involve crossing his own time stream and smacking him upside the head. He could make it up to her now though. He had one night to do it. Well, one night that lasted 24 years.
She said so many things at the table that he wished he hadn’t heard. He should have told her who he was right away before it got to that point. Talking about lying to men. For a moment, he wasn’t sure if he was one of the men that she was talking about. It did start after all, with the diary.
He was tempted to take the TARDIS back. One more adventure with her. Save her from fate again. He knew he couldn’t do that though. They were already there. He knew how it ended, he knew she would save him. He wondered if it would make a difference if she didn’t say anything about their last night if he could have gotten a chance to change things. No, he was there when she died. He didn’t see any way around that. In fact, she started talking about this night as it was getting ready to happen. He had seen so many deaths, but this was one that would haunt him forever.
Memories were coming back to him. The biggest library in the universe, this strange mad woman who insisted that she knew him. She proved that by whispering his name. He always wondered how she felt in the library. Looking into his eyes and him not recognizing her. It broke both of his hearts when he showed up and she didn’t know who he was.
He felt her put her hand on his. “It’s never a good sign when you get quiet.”
“I was just thinking.”
“It still looks weird on you. “
He chuckled a little bit. He had so many feelings mixed within him. Guilt for something that happened a more than centuries ago in his timeline, more guilt that he hadn’t shown her how much he loved her before, sadness, because she didn’t recognize him on this, their last night together meaning this would be the last time he sees her. Then he felt more guilt, because he was happy that he could see her again.
“Why don’t we go order some food since we didn’t get to eat earlier.” He said holding his arm out to River.
“Is there anything that you can tell me that I can expect? I know something is coming. Between the stories and my journal…”
“Spoilers.” Was all he could reply.