I think Sonu wronged Ishqi and Raj (for not telling him truth). She owed them apology and some repentance. But with Ahaan, she was perfect. She did ask him " If she had told him would he understand her like Ishqi did. Would't he thinn once that it might be Sonu's fault to go to party". Ahaan did not have answers to those questions.
It is third person's right to judge Sonu but what she said today was her POV. She stated what happened and why she did not tell the truth. She told it honestly. Yes, she is selfish but she cant say that. It is for us to judge. As a character, I liked her revealtion and dialgues, questions.
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