It was needed

I came to conclusion that maybe this track of Kunal coming back because of Nandini was needed for Mauli to finally realize for real nothing can be same ever again. Mauli will witness how things aren't the same between her and Kunal as she was still living with hope that someday Kunal would be back to her and things would be just like before..this is more like an eye opener for her to see it herself. Also, I think in karwa chauth she will find out his real reason of coming + she will notice how he's behaving then finally on divorce day she will divorce him. That's my take on what they want to show, a final reality check for Mauli.