Now it's high time that Dev puts his words in action and win back Sona's love. The things he is doing now - cry, frustration, anger, stalking etc is not going to help him and only add more misery.
As Sona once told him that you have to show actions/gestures to make the other person feel important. Sona will never go back to Dev until Dev himself takes a stand for both of them in front of mataji. I want Dev to apologize like a man to Sona in front of all in the engagement ceremony and ask for her hand to her parents. Reassure them that he will never leave Sona again not even because of mataji. Then only he can prove that he loved Sona like a man loves a woman.