I think the reason GoT lost me is this:
It's a character-driven show. That was its strength. Interesting, different people reacting to the situations they're put in. That's what made all the previous seasons worth watching. Things happen. Characters have to react. They have arcs.
Tyrion goes from a lovable whoremonger to a position of power. He's conflicted, often endangered. He's got daddy and family and respect issues. All that stops once he becomes part of Dany's retinue. He just....stops having things to do.
Jaime. Heroic knight asshole. Similarly conflicted, endangered, etc....Losing his hand was one of the best parts of his arc because it forced him to become a different person, and that was interesting to watch. But basically after he gets his replacement hand and him and Cersei are on the outs....he stops having anything to do.
Sansa. Probably the character for me that had the widest arc. Hated her at the start. But she goes through a bunch of shit, changes as a person, has to deal with challenges...but once she returns to Winterfell she has nothing to do.
Cersei. Delightfully unlikeable. Has trials and tribulations throughout the show and most of what's interesting about her is how she reacts to the various intrigues. Will she play it cool? Will she go apeshit and try to have people killed? Her arc is maybe a little flimsier than other characters, but the death of her children, her public shaming, those all mattered because she as a character had to react to them all. But once she becomes Queen of Kingslanding she just.....spends a whole season drinking wine for the most part. She becomes a non-character who doesn't have anything to do really because the plot won't let her. She just patiently needs to wait for the Wight Fight to happen like everyone else.
Arya. Started out as one of my favorite characters. The underdog. Being in places doing things she probably has no business doing. You're constantly wondering if she's gonna get hurt, violated, all while the promise of being awesome is continually dangled out there. Her quest for revenge going bit by bit was great. But as soon as she gets to Bravos, all that goes away. Now she's a super hero badass and all the things that made the character interesting are now subsumed by the show's need to cheerlead her and make her awesome. Once she leaves Bravos....she has nothing to do.
Jon Snow. Has a crazy arc that takes him from the lowest of the lows to the highest of the highs. From bastard to Night's Watch to Night's Watch Commander to King of the North to.....NOTHING. After he's resurrected he suddenly stops being a force of anything, and just becomes a figurehead. A cypher for the North's wishes. He's got something to do but it's not surprising. Other than organizing the defense of Winterfell he just has nothing to do.
Bran. After becoming the Three-eyed Raven he has nothing to do, other than sit there, look distant and spoil the plot. Bran didn't have the most interesting arc but I felt like after he became the Three-eyed Raven what little there was for him to do was over. Now he just needs to sit around, tell people where they need to go and wait for the NK to show up.
This all basically tracks with when they ran out of GRRM plots. And the writers just didn't have the wherewithal to try their hand at anything original, so they played it safe, leaned far too heavily on character traits that made characters recognizable throughout the series and spun their wheels for most of a season on the build up to the Wight Fight.