Too many things happened in this episode.
For starters, Sana made a huge mistake by trusting Vishal. But then, it wasn't difficult for him. He could see that she is attracted to him.
Now, what Pillu said to Sana was very right, although the way he went about it was dirty. The whole touchy-feely thing. I was like, look who's talking.
But what he said was the correct inference of Vishal's tactics. Now, his own reason for telling Sana could be stemming from jealousy- the same kind that was evoked when Vishal first entered the house and Sana had saved him instead of Pillu.
Sapna is the best kandha for everyone's bandook. She fights other people's battles. Karishma had it all sorted for herself. I do think though that Sapna went overboard with Sana. I mean, she is a bundle of contradictions. She said she never nominated Sana- but she did during Sana's secret task when Sana convinced everyone to nominate her. When Sana started crying, she faulted her saying she hates women who start crying like a bechaari, when she is forgetting that she bawled her eyes out on Siddhu's chest during that Major task, among others.
So yeah, although I agree with her diagnosis of Vishal, the way she went about it is only going to create the opposite effect. Now Sana would be even more determined to be seen with Vishal(dance task).
Lastly, Urvashi and Niketan had been trying for a long time to break Pillu and Sana's friendship. Today, they were finally successful. It doesn't help that Pillu is easily influenced too and quite jealous of Vishal.