Looks like Vaishali isn't seeing the issue through.. and has become infected by Mrini's ocular defect 😆.... There are 2 problems both at this point insurmountable and one she is sure is aware of and the other she might have inkling of, though she refuses to see it....
Dev is under no circumstance accept Vish.. no matter who gets the Raja Rani Mehandhi first... does she think it is going to sway him by arguing since Vish got it first (though this is doubtful, since Vish is looking at everyone's expression and is smelling something bad... thankfully someone in Shastri family who uses her head...)... did she think she can tell Dev who was ready to walk out, but no Vish got the Mehandi first so you have to marry her???
Also, she might have an inkling of Vish's reluctance.. what has changed that she thinks Vish will be ready for kids now or want to become CB now (another matter, how Vaishali will make both of them to do the act)....
How utterly ridicules... the actress might have few more lines now.. but her character is going to the dogs... it would have been better off if she had demanded at the right time, after the marriage... even asking Rads not to have kids etc...