I was gonna respond to this but Formy summed it up better than I probably ever could.
When you watch something, you are presented with a certain reality. For Game of Thrones, it as all swords, sex, politics, death and dragons. You know what you are getting. Of course I can suspend disbelief for that. That is the world they are presenting. When the same show removes you from that world by presenting you with a person from your real life... the fantasy is ruined.
Not mentioning the name of any show... but if a long-running zombie apocalypse show had presented you with a world in which any time you are overrun by zombies... you had zero chance of survival. They then show you a person being eaten alive by hundreds of zombies... then a couple of shows later that same person didn't actually get bitten once, they crawled under a bin and the entire hoard decided it was getting late and went for an early night... despite the fact there was fresh meat in reaching distance. Yeah.
If you present us with an amazing world, don't get pissed off when you smurf up by doing something stupid. Now honestly, I'm not even close to being as upset by Ed Sheeran than I was with (if one existed) a long-running zombie apocalypse show and the death/miraculous survival of (let's call him Ben) a well-loved character. It was still out-of-place and I expected better from a show of such high standards. Game of Thrones is still life though.