It has been many years since that final meeting at Bad Wolf Bay, and Rose is happy with her life.
Her family is wonderful, her job is fantastic. Perhaps most importantly, she's got John.
They had very quickly decided for a multitude of reasons that he couldn't go on being called the Doctor, so he took on the name of his favorite alias. Things progressed very quickly from there, and Mr. and Mrs. John Tyler (because really, John Smith? It's so normal that it's abnormal) were building their new life together.
She had moved past her old life. The only remnant was the key that constantly hung around her neck. It was hidden from sight most of the time, but whenever John saw it he'd just smile in understanding, and they'd hold each other close, telling old tales and making up new ones- content with what was and what is.