What does Scrooge regret as he watches each scene from the past unfold?

Scrooge has many regrets while he visits the past. His biggest regret is likely his relationship with Belle, as he drove way a young woman who would have been his lifelong coompanion. We also see him lament brushing of the little caroler without giving him money, and his treatment of Cratchit, his loyal employee. Lastly, there's the son of his beloved sister..... He hasn't been good to Fred over the years, but this is the one relationship from the past he can do something about.