Both fall madly in love with Ichha and are sweet and considerate lovers. Both insist on getting married to her despite all odds. Both start their married lives playing the perfect husband. Both defend her against all the taunts and bad behavior from the family in the initial days.
Both come under the influence of Tapasya and start doubting her. Then starts the cycle of torment - in case of Vansh it is both physical and emotional; in the case of Veer it is emotional abandonment. Both drive her to the extent that she decides to walk out on the marriage and make a life for herself independently.
Both realize their mistake in believing Tapasya over Ichha and are repentent.
And here comes the major twist - Vansh who loves Ichha truly decides to end his life as he believes that he can never atone for the pain he has caused her.
Veer decides to go back to his room and what - live with Tapasya and accept her illegitimate daughter as his own and abandon the wife he claims to love?