If you ask methis track is needed. It can't stay like this forever. Prerish is married and something needs to change. As much as this track is tortuous the dynamic will change. As you said it depend on the culprit. Whether it's A or the aunt or taanvi but I believe it's A because he kept shouting at bajaj since the party in front of everyone how bajaj wants to kill him. He kept provoking bajaj. The way how he moved bajaj cigar from his mouth. It makes me so angry. I want bajaj anger to be released. Forget the promise. Another man is disrespecting him.
Anurag the culprit - 99%
MT - 1%
But all three are utilising it to their benefit particularly Anurag. So still this makes him culprit for cheating P emotionally.
RB does the same with P, playing mindgames and convinces her/keeps her with him inspite of all his criminal activities. But RB is grey character so thats how it will be. P married him knowing his real evil face.
Anurag is a ML. P loved him for his good nature.
These are what wil make P see the difference after learning truth behind the accident.