I know many want to disagree with me but why don't you look at it this way:
He was the one who sacrificed his love[Trishna] for the happiness of Rajdeep and Kulraaj. He was the one to stand with Tanya when the "bad" happened to her. He was the one to marry Tanya and be able to live under the same roof as Trishna and yet be calm enough to go through Trishna's words without saying something himself.
Raj was the one who stopped Tanya from killing the child. The one who took care of Tanya, the one who any girl, even I would want to choose as her life partner. Ok, so Yuvraaj may not be perfect but no one is perfect. Everyone has their flaws.
Come to think about it...in today's life who sacrifices soo much for his family, for the ones he loves? If the creatives wanted, they could have made Nupur call Raj a selfish man but after this, I don't think anyone will point fingers at Raj.
He is like life line of Vivaah. He is the strongest character. Someone who may cry once or twice but it's bcs something really close to him is getting away...he cried when Trishna went away from him and Rajdeep said he loved Trishna. He cried then bcs he didn't know who to choose. The girl he loves or the guy that he considers his brother. Who wouldn't cry?
Overall, I'd say Raj is a pretty strong character. He went through all the phases in his life but never once did he make it seem like he was doing anything for himself. He knows that if anything happened to Tanya, than Kul and all her family will be heartbroken. If Trishna didn't marry Rajdeep than Rajdeep will be sad...and to stop all this from happening Raj did anything that he could to stop it from happening...even if it meant breaking Trishna's heart bcs he knew that RD will love Trishna more than him and Trish will be happy with RD...
I simply adore Yuvraaj...