When she saw Dev for the first time after his return from US, she had prayed to Goddess to give him pain. She wanted him to be alone. She wanted his family to isolate him. She wanted him fall in his own eyes. She started to get cozy with him and flirted with him only with the above intention. She wanted Dev to propose her, Shaurya to oppose the same and the brother's to fight over it.
Well her flirting didn't give the desired result. Dev was uncomfortable around her. Then the attack on him, her MU cleared and she went close to him. He opened up to her about his feelings for Nithya. A new bond was formed between them when she took him to meet Payal and gave him Nithya's diary.
Then she took a U-Turn. Made him a stranger again. Dev by now had gone more closer to her than he himself thought. His feelings about her were no longer platonic which strangely he was unable to explain and it defied every logic.
Her actions were mysterious and whatever he had known about her , her actions contradicted those. Every interaction with her ended in confrontation. That pained him. Every time she told she loved Shaurya it started piercing his heart.
She was giving him pain, more pain by her actions. In addition to that Sakshi blasted him for hiding info on Payal, his mother wants to take him back to US after Shaurya-Durga marriage. He does not have a single person to talk his feelings to. He is literally alone in that house trying to find where Nithya is.
Ideally Durga should have jumped in joy seeing Dev like this. Her prayers are being answered. Her victim is living in misery the way she wanted and the day he knows she is Nithya obviously he will fall in front of his own eyes. So what more does Durga want for Dev. Her punishment to him for abandoning her is being given quite well.
The way she had wanted him to be by her side, he is pining to get Nithya by his side. And as truth eludes him he lives in more misery and if he cant get the truth before her marriage most probably he will live his life in eternal misery.
But the irony of the matter is that Durga is not happy seeing him like this. She had asked for his pain, but when it is answered she is equally troubled. The confrontations not only leave him in pain, it also leaves her in equal pain. Both are troubled, both are pained. If she wants she can end his pain. But now even if she wants it she cannot do it because she has gone far ahead in her mission and anything out of ordinary will be equivalent to compromising her identity and security.