It could mean that stories end in a way that is typical or expected for that kind of story. Just like how most romance stories have a happy ending.
Well, when we say 'stories end as stories do,' it might imply that they follow a certain pattern or natural course of conclusion. Maybe it's about resolving conflicts or reaching a logical endpoint based on the story's setup and themes.
When we talk about this, it often suggests that stories wrap up in a way that's consistent with common storytelling conventions. It could involve character development reaching a peak, loose ends being tied up, or a sense of closure that feels right within the context of the story's genre and tone.