Heroines don't win because TRP audience apparently like to see them struggling and crying.
The girl has to be "mahaan" sacrificial and selfless to unimaginable extent to qualify as a heroine. It does not matter even if she ends up being foolish in this task.What would have taken CVs to make Pragya enter on TaBhi's wedding after the lead and expose her, by brining Nikhil+proof with her? Nahi na... they have to show us how she tries and tries to do something but ultimately loses to the villains or someone helps her out.