A well made decision to end a relationship does not need to be ended on a bad note by walking out in anger or impulse. Vividha has just extended her hand of friendship to Ravish. She has closed the doors to any possibility of Ravish or his family accusing her of giving mixed signals. She has slowly but revealed her true self and what lies in her heart to all involved (except Atharv who just got himself back two days ago). She has no need to be impulsive because Atharv is angry. She knows how to explain things to Atharv but the relationships...the talk that Suman gave about non-blood relationships, the fact that Vividha knows Suman, Ravish and Adithi have all been kind to her, she has no need to disregard them because Atharv is her priority.
She has her own persona and she has her own opinions about any situation just like Atharv. And She knows that given the opportunity to talk to Atharv she can get him to see what she wants and why she wants it that way. Just like she wanted to wait for Kailash to give his blessings, Atharv didn't agree but he respected her wishes because he understood her reason for it. He didn't suspect that Vividha was cheating him then.
Similarly, when Vividha gets to explain her side of the story clearly to him without hiding anything he will understand or share with her a different perspective that maybe she has not thought of. That is what Vitharv do and that is why they are a couple that will ultimately make their way back to each other every time.