Headcanon

What if… Amy and Rory  when touched by the weeping angel, got zapped back to Pompeii and split up (hence river’s afterwords: don’t let him see the damage). Rory went to Rome and became a Roman while Amy stayed in Pompeii and became a soothsayer. And Amy couldn’t leave with the doctor because they were in their tenth and 12th regeneration, so she didn’t recognize them.