User blog comment:Etindel/That did NOT just happen!/@comment-15843945-20130606194856/@comment-6735528-20130610182539

There is no plot fault. The Red Wedding was planned ahead of time with Walder Frey, Roose Bolton, and Tywin Lannister. I would imagine Tywin initiated the plot when he heard of Robb's marriage, seizing the opportunity and granting House Frey protection and rewarding House Bolton. This is why at one point earlier in the season Tywin states that Robb Stark's days are numbered. The wedding was meant to lure the Starks into an elaborate trap to eliminate Robb and force the surrender of Riverrun.