On Good path, there is a choice for almost every girl to have a better life in one way or another.
On Dark path, not so much. Instead the girls will have more training for becoming members of the organization.
You speak of Sarah. If you choose to be nice to her, not corrupt her, and make the decision to be on the "hero/harem/good" path, then her future is much more positive.
(I know it's vague, but I don't want to spoil any specifics.)