Perhaps Snow only thinks that she had something to do with Daniel’s exit. Maybe she doesn’t know that he was killed. It appears that Regina keeps her secret even until after the king’s death (when they embrace). Think about it, Regina keeps her secret for nearly 10 years, right? We have know reason to suspect that SW has found out otherwise. Maybe she only thinks that Regina is upset about Daniel’s departure or that Regina is jealous of the kings love of SW as seen in the Genie episode. Maybe what we have assumed (jealousy.. etc) is actually what SW thinks.