Why not a deal with the devil?

I know one could argue that Aaliyah can't be trusted, but now that Pragya was going to leave Abhi forever anyway as she left with Maa to Paalghar, why didn't she make a deal with Aaliyah so that Tannu and Abhi can be separated by Aaliyah?

She could have put a condition that she will leave only if Aaliyah breaks TaBhi marriage.

I know Sarla Maa was adamant to leave immediately but then Pragya could still tell Aaliyah by calling her or somehow that she has given up and leaving Abhi forever. That way Abhi could be helped too from getting married to the worst woman in KB world.

I wonder why Pragya never thought about this. Did she think Aaliyah is not trustworthy? But then she was going to leave TaBhi to themselves anyway, why not give a last try?