Where is her master in all of this? Isn't an apprentice supposed to be with her master to, you know, learn things from him?
I think the idea is to show how Ahsoka has matured and become more independent. Also, maybe having her spend less time with Anakin is to justify why we never saw her with him in ROTS. And maybe being apart from Ahsoka is a factor in Anakin becoming more unstable and closer to where he is psychologically in ROTS.