Disclaimer: I don't own any of the characters, though I wish I owned Amy so she could've stayed a good character through her whole run as a companion.
Forgiveness
As she stood in the open doorway, watching the sea of stars drift by, Amy repeated only one thought to herself: he would forgive her. He always did.
Rory was predictable that way. She could picture the look in his eyes when he found out about this, the frown that would crease between his eyebrows, the downturn at the corners of his mouth. Even his face was predictable—and she was so, so tired of predictable.
All of space and time, that's what the Doctor could offer her with his magic blue box. A life in boring old Leadworth, that's all Rory had. The decision, if one could even call it that, was not hard to make.
The moment she stepped inside the TARDIS, her heart filled with excitement. The prospect of adventure and the far-off worlds she had always longed for heightened her senses until she could see, hear, smell, feel everything ten times clearer than she had before. The blinking lights pierced her vision, almost overwhelming; everything glowed orange and silver and green. Each tinkle and clank from the machinery registered in the front of her mind instead of the back. Whiffs of metal, salt, and a strange half-burning, half-cooling smell mixed with the gentle puffs of soapwood air that blew every time the engine in the center of the room pumped inside its glass column.
This room was everything she had spent the last fourteen years dreaming of. Fourteen years, two-thirds of her life, spent waiting for the imaginary friend that she refused to stop believing in. Oh, how she had sometimes wished she could make herself stop. But now the Doctor was as real as anything, her Peter Pan whisking her away to a fairytale Neverland where things like gravity seemed absurd and she would never be bound by the inevitable growing up.
Growing up.
"You're growing up so fast," everyone has said when she and Rory announced their engagement. What they really meant was, "Oh, but you're so young." Too young, according to her aunt, to even be thinking about getting married. Your brain isn't done developing until you're twenty-five, you know. Marriage is not an impulse decision. What could you possibly know about love, anyway?
It had driven Amy crazy at the time. Rory was her best friend, her life-long confidante. He had always been there and would always continue to be there—so it only made sense that they should get married. It was natural; it was right. She loved him in a deep, constant way she had never loved her first few boyfriends. It was a gentle sort of burning, like coals under a campfire, without the passion of bright flames but also without the brevity. So maybe she wasn't in love with him, whatever that meant, but she was positive that she loved him more than she had ever loved anyone else.
And so it was that, for the first time in her life, Amy Pond felt guilt at not feeling guilt. She should have thought of Rory as she raced from her bedroom towards the sound of a now-familiar whooshing. She should have thought of him as she leapt down the stairs three at a time like she had as a little girl. She should have thought of him as she crunched barefoot through the grass and dew seeped up into the hem of her nightgown. But she hadn't.
He hadn't even crossed her mind. She had been thinking only of herself and her Doctor, but, she supposed, she had always been a little bit selfish. She had never quite figured out the balance between what she wanted and what anyone else wanted. It seemed to her, at times, that she could not continue being herself if she spent too much time considering others, and she was nothing if not purely Amy.
But still, what kind of a person runs off with another man on the night before her wedding and isn't the least bit sorry?
He would forgive her. He always did.