Robb was the worst GGRP ever, but I think it was his mom that ####ed everything all up.
In a nice twist from the usual, look at how much love changed the world for the worse, instead of saving the day.
If Robb doesn't fall in love with the Chaplain girl, he marries Frey's daughter and has a huge army to crush the Lannister's.
Instead, because he falls in love, he dooms his bride, himself, his mother, and destroys the largest army for good in the world. The entire fate of the evil Lannister family was re-written for the better because Robb fell in love with some girl.
Crazy.