Raman is also not doodh-ka-dhulla-hua. He also has his bad side.
Honestly, I think Romi, Raman, and Simmi are all very interesting characters. As another poster pointed out, as the youngest boy, Romi is able to get away with a lot of things. We've seen how the whole family is so relaxed with him, even in regards to studies. Raman is the only one, it appears, who seems to keep some sort of tab on Romi's activities and studies. And aside from the mms scandal and that almost drugging Mihika incident, he's been shown as a realistic guy. I'm waiting to see how the CVs address those two subjects. Rest assured, its going to definitely fracture the already tenuous relationship between the Iyers and Bhallas.
And Simmi's behaviour also makes sense, to a point. She didn't like Ishita before because she didn't like Vandu. Vandu and Simmi have never gotten along. And Simmi's dislike of Vandu got transferred over to Ishita. Once Ishita proved that she was not Vandu and that she actually cared about her, Simmi started genuinely respecting her. That also is very realistic. And I can totally see where Simmi is coming from during this conflict. Why should she believe Ishita's claims over Parmeet? She's known Parmeet for over 5 years and even has a child with him. Whereas she's only known Ishita for about three months. Of course she'd trust the person she's known longer. And plus Ishita has the evidence against her. The messages, Sarika's testimony, and the fact that Raman and Ishita don't share a relationship. Anyone in Simmi's place would believe Parmeet over Ishita. And as for Sarika telling the truth, we as the audience know its the truth, but how does Simmi? Sarika severely compromised her credibility when she originally lied about the Ishita and Parmeet issue. If a woman could lie before, what's the guarantee that she's telling the truth now? And plus, let's not forget Parmeet's super innocent act. He's been that way the entire time Simmi's been with him. She cannot even fathom him doing something like that. Nor does she want to. If Parmeet really turns out to be a creep (we already know that he is one but she doesn't) her entire life would be destroyed in the short run. She'd get her heart destroyed, her marriage broken, and her daughter would lose a father. Simmi has a lot on the line. Plus when you're in love, you don't want to think badly of the person you love. Heck even Raman went through the same thing with Shagun. Through flashbacks, we've seen how it was super obvious that Shagun was having a thing with Ashok (only letting him apply holy colours, lighting up around him, etc). Yet even with all these visible proofs, Raman refused to believe that she could be cheating him for the longest time. So I can totally see Simmi believing Parmeet over the others. It's human to not want to get your trust broken, to want to trust the one you love. If anything, I feel like Simmi is the greatest victim in this entire situation.
And Raman. Let's not forget that before Ishita came into the situation, Raman was a jerk. He didn't take care of his daughter, was basically mentally abusive to her, the the point where his family even had to interfere. On top of that, he was brash and rude with everyone. It's only through Ishita's influence that he's begun changing. He's left behind the alcohol. He's started becoming a better father to the point where Ruhi is beginning to become very attached to him. He's also become kinder with people as evidenced when he didn't call Ishita barren during the pregnancy drama and was so diplomatic with Sarika. He went through changes.
And I'm sure that Simmi and Romi will also undergo these changes if the show continues to be on for long.
And LOL I have no idea about Rinki. She's such a non-entity at times. The CVs should really begin using her character.