Who is Sasha? How does her life compare to Becky?

Sasha is a new identity assumed by Becky in order to engineer a "chance" meeting with Chloe's best friend, Livia, at an art event, followed by another run-in at a yoga class. Becky continues to live life as both Becky and Sasha. Sasha infiltrates Chloe's group of close-knit friends and ends up gaining a job outside her genuine work experience. Sasha leads a life that is far more exciting than her life as Becky.