Looks like it and Vish may have been in cahoots with him. She is taking this revenge way more personally for a dasi of Bela's. It seemed like she lost her lover and was out for their blood instead of just working for Bela.
If Vikrant had married Bela, he would have become Nagraj. He would have gotten naagmani too. After that it would have been a simple matter of killing Bela and Vikrant would have been free to marry Vish, thus making her Naagrani.