While its very tragic, am I the only one here who thinks "Robb had this coming, and brought everyone he loves in to doom"?
Robb Stark was immature and young and was playing the Game of Thrones versus an expert, Tywin Lannister. When you step back and look at the situation, I think it is easier to say that Robb just made mistakes that youth make, not that he deserved what happened.
I actually disagree. Robb played a part in causing the Red Wedding, of course, but I think the biggest culprit, the person that really brought all of the males in the Stark family to doom, was Cat.
Walder Frey would have been mad at Robb, but he'd been slighted by nobles his whole life. He wouldn't have liked it, but if Robb were still powerful he'd have grinned and beared it. But Robb wasn't still powerful, because his army splintered right about the time that his mother decided to let Jaime go. That one move gave up Robb's biggest leverage piece, turned one of his biggest supporters (and eventually that large portion of his army) against him, ruined morale, and eventually left Robb in a weak enough position that the Freys and Boltons of the world smelled blood.
This was eerily similar to how Cat's spontaneous decision to kidnap Tyrion led directly to the deterioration of Ned's power base and eventual fate.
Or how Cat's nastiness to Jon Snow led directly to him being sent to the Wall...so that he wasn't around to be the man of Winterfell with Ned, Cat and Robb and their retainers all out in the field. If Jon, Cat, and Cat's guards are at Winterfell does Theon's little uprising that led to a displaced Bran and Rickon ever happen? I think not.
As far as the Stark family goes, Cat was the devil.