Secrets and Spoilers
"Its not running away, not really" the Doctor tells himself as he speeds away in his tiny blue box on his way to rescue a much younger version of River Song. No his past incarnations have learnt the hard way about avoiding confrontations with the parents of his companions, even if those parents have travelled with him as well.
No, best to leave now before Rory discovered that his daughter was the very same girl The Doctor had openly flirted with and (unbeknown to her) bragged about kissing mere adventures ago.
With hindsight his and Rivers blossoming romance was one secret The Doctor wished he had kept to himself. But there was little he could do about it now, except hope that when he had finally reunited Rory with his first born the gratitude the roman would feel would override all of the new father's desire to hurt the Timelord.
Admittedly while The Doctor had known it was only a matter of time before he found out just who Professor River Song was, he never would have guessed that she was Amy and Rory's daughter. "I suppose I'll never make godfather now" he says to the now empty control room, in an attempt to cheer the TARDIS up.
Thinking back he had seen the similarities as he quickly glanced nervously back and fourth between the woman he loved and her parents. Though he had been quick to realise the implications of her revelation, he had really only just begun to process it now as the time and light years took him further and further away from the asteroid.
Its better this way he thinks, as the asteroid slowly becomes a tiny dot on his view screen getting smaller and smaller until at last even his sharp eyes cannot see the rock anymore. This way he should be able to spare putting Amy and Rory through any more suffering, unwilling and unable to see them look at him with those empty heartbroken eyes that betrayed their composure revealing their true feelings.
He sighs as he hits one of the buttons on the control, the large red one. "The battles just begun" he thinks as his eyes flicker back onto the screen.
"Just wait" he says his voice deeply serious.
"Just wait, I'm coming to get you"