Okay, to start off, I dont personally think they will make Rishita into a vamp. I feel like she'll have grey undertones but never be a complete vamp.
Now, onto this episode, Rishita is either extremely insensitive and has no tact or she's knows what shes doing and is doing it on purpose.
She is actually emotionally abusing Dev because the way she is wording her sentences like " I left my family and everything behind for you, dont you care about me?", shes jealous and is trying to guilt trip Dev into being on her side and her side alone.
But shes also going about this the wrong way. I mean, if you're trying to get on your husband's and his family's good side, I think the insensitive B*t*h act is the wrong way to go. Should her fist act be to gain forgiveness from Dev and show him that "hey, I love you and we'll work on getting your family's forgiveness together ". The way she is moving not only makes her look insensitive but also puts Dev in a tough spot because now it's his family vs his wife. And this will probably be a track in the coming future because I think Shiva is definitely close to blowing up on Dev.
If we move from Dev to her attitude with Raavi. Literally, WHAT IS RISHITA'S PROBLEM? Since shes come into the picture, Raavi has not said a word to her or her Dev and yet Rishita seems to not want to let go of her prejudice against Raavi.
The way I see it, Rishita, despite getting Dev in the end, is still extremely jealous of Raavi. Everyone in the family is trying to make Raavi comfortable with her situation and Rishita doesnt like that and that leads to her throwing insults like that "our marriage wasn't by force" wala comment. And then when Dev tells her off after that and walk off, showed her that shes still not first priority.
You know that saying about kids doing bad things and getting in trouble to gain attention from their parents. Kind of feels like that.