I genuinely don't believe Saanjh will turn negative. She has so much love for Arjun, and time and time again she's sacrificed her own happiness for him.
I don't think she will come in between Maya and Arjun, but after Aswhin brainwashes her with false information, she will certainly join forces with him to save Arjun from danger aka Maya (or so she thinks after Aswhin manipulates her).
Whatever she's going to do, it will be for Arjun, to "save" him.. not realising it's all a ploy by Ashwin.
The drama he pulled re: the suicide was brilliantly done, and he's got away with it so it won't be surprise me how he gets Saanjh wrapped around his fingers to get what he wants.