In the party, she didn't like the fact of lying to Raman that Ruhi is Ashok's daughter.
Then in front of Tanu, who was making fun of Raman's condition after this lie, Shagun got irritated. She reacted saying that her daughter's identity is being faked and even her reputation is being tarnished. And later, she also told, after these long 6 years, that she has been playing and doing according to Ashok's orders. Then she became upset about their marriage. It is all giving hints about her realization that choosing Ashok was a bad idea. Though it's a petty realization, cos, she got happily surprised when Ashok said that he would marry her this time of course. But, it's the beginning of Shagun being punished and tortured for her misdeeds.
What do you say friends?