She uis definitely not jealous because Samrat is more romantic than Mayank and she is not being protective..
I think she is getting jealous because Babuji has said Gunjan is his only daughter as she is ideal and now Nupur sees Gunjan doing all this which even she did and Babuji got angry on her for that.. Now Gunjan is doing all this but still she is good in Babuji's eyes... She is angry on Babuji and thats the main reason behind this jealousy...
Whatever, I dont think after watching more than 1 year of MJHT that any such thing can happen between Gunjan and Nupur.... CVs have gone totally mad..
Also I think this will go on for some time as a new track as they have made a special promo on 2 behno ki judaai...
But everything will be good in the end as always :)
Still CVs have made mess of Gunur relationship... :(