I'll reply in more depth after I watch the episode, but here's something I need to say.
I'm the eldest of three children. It's my job to make sure that my brother and sister are being steered in the right direction. If I see a guy kissing my sister, I will not only smack the guy, but smack my sister as well. If I kissed a guy in public, I wouldn't want my sister smacking me or anything, but yes, she has full right to tell me how she feels about it.
I'm not a fan of PDA so naturally, I'd get angry if someone I knew and loved were all over each other. I'm not saying SaJan were doing anything of that sort- I mean c'mon it's a peck on the cheek for crying out loud!
I think the problem here is the fact that Nupur is being labelled as the girl with no morals, the one who's been destroyed in this big bad city just because she fell in love and wasn't afraid to admit it. Nupur is a drama queen. She wanted EVERYONE to know about her and Mayank's relationship, whereas Gunjan's more quiet and likes to keep it to herself. Just because Gunjan didn't admit her love for Samrat in front of her father doesn't make her the good daughter and Nupur the bad daughter.
From what I've seen, both sisters share the same morals that've been instilled in them. Nupur tells people what she thinks but Gunjan doesn't. These sisters are poles apart but NOBODY has the right to differentiate between their morals. Nobody can say that one daughter is better than the other. They've both made their share of mistakes. Nupur has and Gunjan has.