Let's briefly back it up to recap: Bran sent out his ravens for one of his most perilous visions to date. As they flew over the scores of White Walkers, the young Stark realized that, yes, the continent is truly screwed if they don't act fast to annihilate the Army of the Dead. So, he sent word to the maesters who wrote off the vision as nothing but a childish cry for attention, despite Sam's protest.
Back at home, Sam stews in his resentment over the maesters not taking him seriously, while Gilly dug through some Grade-A maester tabloid material. It turns out, one of the maesters annulled Rhaegar Targaryen's marriage and then wed him to another woman in secret. This could mean that Rhaegar and Lyanna were married and that Jon could seriously be the rightful king. If so, it's a good thing he hasn't bent that knee.
Unfortunately, Sam refuses to listen to the game-changing gossip Gilly's handing him on a silver platter and instead decides he's going to pack up and bolt, saying "I'm tired of reading about the achievements of better men."
We get it, Sam: You want to prove you're a big man who does big things, but for a moment, put aside that ego and listen to what the beautiful, smart, courageous woman in front of you is saying! It could change the entire trajectory of the Seven Kingdoms.
Thankfully, I wasn't alone in my frustration as hordes of fans took to Twitter to make their points.