You know I too was spoiled for this exact fact. I stupidly read the comments of some torrent and it said robb and his wife were gonna die at a wedding. But I didn't believe it and actually totally forgot about it. I only remembered after Bolton's armor was shown, so I wasn't too spoiled but it still sucked because the rest I knew. Catherine's death came as a surprise though. The slave battle not being shown was a bit of a cop-out indeed, but for me it was compensated by Danni's facial expressions when she heard of the victory. She radiated power so crazily good.