Last night's Game of Thrones was the first of the season that really gave the impression of dominoes falling. From the outcome of Tyrion's trial, to Petyr's final moments with Lysa, to Daenerys' consummation of her flirtation with Daario, all of the pieces the show has arranged are beginning to tumble. This is a show where it's so easy to forgive whole episodes that seem to function as place-setting (with perhaps one big action sequence or shocking twist to tide the audience) because we know how satisfying the denouement will be.
Fans of the show who have never read the books probably could have predicted Lysa's fate or Oberyn's decision. They are eminently logical and serve the story well. But even if you saw them coming, it had to be satisfying to see them play out. Lysa's foolishness was plain from minute one of her re-appearance. By locking herself and her son in the Eyrie, she's made no friends and is forced to rely on one of her oldest, Petyr, who has become a legitimate lord but plays on his teenage manipulations of her.
It's sad to admit that Petyr chucking Lysa out of the moon door is as close to this show gets to a genuine hero moment these days. We've been waiting for Lysa to receive her comeuppance since she almost chucked Tyrion out the Moon Door in season one and spurned her sister's requests for help. Lysa's note to Catelyn, which prompted her kidnapping of Tyrion, was one of the instigating events of all the subsequent chaos, especially Ned's beheading. She's raised a brittle baby of a son who is totally unfit to rule a mighty kingdom, and she's so jealous of Petyr's attention to Sansa that she almost pushes the poor girl to her death.
So it's great that Petyr knocks her off, but my God, what a cruel way to do it, leaving Lysa with the final thought that his heart always belonged to Catelyn as he shoves her to her death. Weirdly, as cold-blooded as the moment is, I don't think Sansa should fear death from Petyr, as he holds genuine affection for her. But she should fear other things, since that kiss he planted on her is probably just the start of something. Sansa represents everything Petyr wants: his unfulfilled love of Catelyn, plus the power and influence of the North, to which she is heir. Be careful there, Sansa!