I want them to show Bua as someone who genuinely cares about Shivansh but also, she has her biases and she thinks Prarthana is not the right person because of her status etc. She can create conflicts between Prarthana and Shivansh, but it would be nice if she slowly notices how Prarthana cares for him and stands up for him. Ideally, this should be a sign for Bua to see that Prart will fight for him even without knowing the full story.
With Shivansh, Prarthana doesn't feel the need to be silent and accepting, she fights back. She knows the truth about their relationship, and when he is in the mood, he is quick to remind her, but she knows he doesn't consider her inferior. It gives her the confidence to speak up. This Prarthana is very different from the newly married Prarthana who didn't take a stand for herself, and this her more....likeable for people who weren't a fan of her previous personality (I guess Bua falls into this category).
Also, initially, Bua wasn't in favor of Shivansh's revenge because she didn't want this for him, she wanted a good life where he was happy. If she really loves him, then she should see that Prarthana is also trying to do the same thing, she is trying to bring him out of his badla and she is keeping him happy.
As for Sonalika, the way I see it, she didn't make him happy, but being in a relationship, being cared for, someone demanding his attention and his basic need / instinct to be a good partner kept him happy. Shivansh is the kind of person who is looking for a home, and even a rough idea of it will keep him out of his grief / bitterness. Also, Sonalika knew him before he found Smita. There's a definite shift between then and now, she won't be able to handle this side of him - she's accustomed to "happy" Shivansh, not this broken version of him who's obsessed with his revenge. I'm going to ignore the business aspect of their relationship because that's pretty self-explanatory.
I hope they don't make Bua a complete vamp and I don't want Sonalika to be out and out negative. She can confront Shivansh and ask him to explain himself (that's her right), and then I want her to leave him because she shouldn't run after someone who didn't stop to think about her before marrying someone for revenge.
pranali ka is hilarious 
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