Where did it went wrong? or just a unlucky river card...!

Although you were super unlucky in this hand I feel that raising the river was a mistake. This second King on board in my eyes is very scary given the fact you were getting called right through. He called your raise so 66/1010/QQ/K10/QK Are a very easy possibility KK as well but who can put someone on Quads right. I think that only if the board didnt pair and no diomond came as well then raising would be an option. Very unlucky though.
I get a little frustrated with these types of hands because even though you turned the world he was never folding.

This depends on your opponent, if he is a loose fishy player, your raise is ok coz he could have any K. Against a tight player, Id call, as he`ll fold most of the hands that you beat, probably only calling with AK (which he would have 3bet preflop) or AJ which splits the pot.