On the surface, Ruhaan, Mishti and Veer might seem to mirror Kunal, Mauli and Ishaan. I feel the equation is different. Ishaan had felt Kunal was Mauli's choice and therefore he had given her up to Kunal so she didn't end up feeling guilty. The situation is different now. Mishti will fight her feelings for Ruhaan very sincerely and it will be Veer who realises what her heart actually desires, but mind refuses to comply with. He will understand Mishti is ignoring her own feelings, much like she ignored the engagement ring she wanted for the sake of peace. I think he will probably have to teach her to face her feelings than ignore them. Back in S1, Mauli didn't express the feelings she had for Ishaan verbally because she did not want to make a mistake - Mishti refuses to acknowledge her feelings because she feels that would be the biggest mistake. I hope the writer puts it forth without making a mess.
If they do this I am game. They should not rush the romance and explore the conflicting emotions. Its not wrong to fall in love after you've committed to someone but its what you do after you realise your feelings that should set you apart.