It wasn't easy for Riddhima to take revenge from Vansh because her trust wasn't weak enough.
Ishaan was supporting Riddhima to take revenge from Vansh and Maahi was supporting Vansh to take his revenge from Riddhima.
Then she just asked, "How will you take your revenge?"
He kept the same idea as Vansh did, "By marrying you in front of Vansh."
But Vansh's idea was just a drama. Ishaan was keeping pure feelings for Riddhima but Riddhima wasn't.
She disagreed, "No, I am not going to marry anyone. I am already his wife."
He said, "But he has cheated you and your eyes are now a witness too."
He was trying his best to not let the seed of trust grow in any way, "Eyes can lie too because my heart is not ready to believe it."
Inside she was really broken but from outside she was pretending that nothing happened.