The fact that you don't attend games makes this a very strange question - you're going off what people have told you - relaid information is often exaggerated.
Personally, I don't hear a lot of moans in the Lower Gwladys and at away games, I'd say he's the main player to sing about. For every moan there's 100 times more people singing 'We've got a diamond...'. There's the banners in the Gwladys Street. He gets stick, yes, but every single other player does.
It's easy to read into the saga with what reason fits for you but the fact is none of us know the real reason that Barkley has not signed the contract on offer (whether it's been on offer since last April or February 2016).
Blame it on Koeman, blame it on Barkley, blame it on his agent, blame it on the city, blame it on the fans - hopefully we'll know reasons one day but until then it's all speculation.