While Once Upon A Time had a consistent cast for the majority of its 7-season run, Meghan Ory's Ruby disappeared just after her role had begun to expand in the series. In Storybrooke, Ruby was a waitress at Granny's, who longed to have a life beyond the small town; in the Enchanted Forest, she was a subversion of Little Red Riding Hood. As both the wolf and the victim, Ruby was a critical part of the show as someone who was both pure at heart and controlled by a darkness she didn't know she had.

https://screenrant.com/once-upon-a-time-what-happened-ruby/