Wasn't the answer to her not mentioned in ROTS simply the fact that (Spoilers) left the order?
On her role in the saga I recommend the following read;
And perhaps with Ahsoka by his side, Anakin could have found the strength to reform the Jedi. When she tells him that she is going to leave the Jedi Order, she surprises him by telling him that she knows that he's thought about leaving the Order as well. Ahsoka gets him in a way that no other Jediónot even Obi Wanódoes, and she sees not just the good in him, but also his struggles. The Jedi didn't pay attention to Barriss' frustrations and largely ignore Anakin's divided heart until it is much, much too late. **
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