Losing Rose was a torrent of pain ripping through him like a waterfall, tearing him apart from the inside.
But that was a softer hurt compared to losing Donna, to losing Amy, because at least Rose didn't die.
The person that was Rose lived on, in his memories, in that alternate universe with another version of himself. Sometimes he dreamed of them, his Rose and that other Doctor, and they were running through time, loving and living on. They had found a way to travel. He knew they would. With his knowledge, and with Rose at his side, anything was possible. More days than not, everybody lived.
But Donna was dead. This woman with her face, walking around with a universe hidden inside, had no idea how important she was, how brilliant she could be. He couldn't think of her loss without a sledgehammer of guilt smashing into his chest, caving him in. No matter how many regenerations he ran from her, he couldn't lose that feeling.
And Amy. Wonderful, beautiful Amelia Pond. Williams. Pond. His friend, his family. She chose Rory over him, and a part of him understood that. Rose had chosen her Doctor over everything else, over Mickey, over her family, over her life, but it still hurt to think that his little Amelia Pond didn't need him anymore. She loved him, but could live her life without him. He wondered if she had ever regretted that choice.
Now he was alone, again. Countless regenerations after giving up Rose. Countless worlds after losing Donna. Countless companions after his darling Amy.
He was alone.
Would it even be worth it to ask someone to travel with him again? He would only lose them in the end. Or worse, almost worse, they would choose to leave him. He wasn't sure he could face that again. He wasn't sure...
but then, one day, back on Earth after multiple centuries of completely avoiding that heart-breaking planet, he came across a girl. An ordinary 27th century girl, with a boring job and ordinary life, but he saw how she could be extraordinary.
How could he resist?