to answer your query which is A VALID
Vidhi feels she's a oldest bahu of the house first and foremost and then a wife and a mother.
She is unable to face and sort out her own problems with her husband; and therefore, she focuses on other family members and their problems. I suppose she thinks as the oldest bahu it is her duty. Actually no she doesn't suppose, when she came to this house G3 made sure Vidhi knew that she's the oldest bahu of the house and have all these responsibilities.
I actually feel sorry for her because although it is her fault that she's not sorting out her own marriage, she doesn't want her dewarani's to go through the same treatment as she went through. She makes sure that she's doing the house work so the dewerani's have time to spend with their husbands. She puts her marriage at stake - highly stupid i must say, so the others can benefit.
She's unconscious of the fact that she's putting her marriage at stake only because she's been programmed that way by G3. G3 is forever saying Vidhi is the oldest bahu and she has all the responsibilities. What is even more sad is that Pankaj does blame his wife; but doesn't recognize the source of the problem or face the problem aka his mother.
I remember in the initial episodes when Aarti and Pari were serving the breakfast, G3 told Vidhi its time for her to sit down since she have two dwverani's serving everyone. The chair beside Pankaj was empty and some other chair far away form him was empty. Vinidi was gonna sit beside Pankaj but she changed her mind last minute and went and set far away from him. Pankaj was shown sad; however, G3 was shown smiling indicating that she liked Vidhi not sitting with her husband in sense that she showed respect towards the elders sitting on the table. She has shown this sarcastic/genuine smile directed towards Pari who was serving only Partik aka not showing respect to the elders in G3's eyes.
a far as the children are concerned. I don't think it was her choice to send the children to hostel. since the elders in the family decide everything and are big on "achi tarbiyat", i'm pretty sure they decided the sending of the children to hostel. Yash's children just aren't of age or they would have been in hostel as well. Moreover, after Arpita everyone treated P&P with little too much love and care so I don't think Vidhi could say anything to them two as she can to her own children.
So yes Vidhi should straiten out her marriage and issues but how she is, isn't entirely her fault. Besides with Yash being an exception - only to an extent, I don't think the sons of Scincdia household have much of a backbone to stand up for their wives.