Ah, the folly of young love! Weve all been there before. Nothing else matters in the world because someone has stolen your heat. But hey, this is Westeros; pull your head out of the clouds, Robb! This is Walder Frey were talking about! Robb needs Freys permission in order to cross the Green Fork river and move his army south and the only way the curmudgeon (and thats the nicest way to describe this slimy SOB) that is Lord Frey will allow this is for Robb to agree to marry one of Freys many daughters. Robb reluctantly says yes, but soon finds himself deeply in love with young Talisa (or Jeyne in the books), marrying her not long after. The thing thats hardest to take is that he knows hes breaking his word with a man that everyone around him, his mother most of all, has told him cannot be trusted. But honour comes as second nature to a Stark, so Robb returns to Frey to admit his wrongs and ask for forgiveness. Of course, the fact that he now needs Freys army more than ever plays a big part in it as well. To make amends, Robbs uncle will marry one of the Frey girls and everything will be right as rain. Unless its the Rains of Castamere were talking about. In that case, you end up with a dead wife, dead mother, a decimated army, and your head detached from your shoulders. Maybe the core lesson here is simple: listen to your mother.