My gut instinct is that Charlie has limited capacity to sense other peoples feelings, or know what is appropriate social behaviour.
He just seems to have blinkers on all the time - you'll notice that he never really interacts with Josie. He just talks at her about things he thinks he knows a lot about. He seems to be driven by pure inner emotion. He does what he feels like doing. He orders crap because he feels it will look good.
That said, he's very into detail and organisation and grooming. Everything needs to be perfect. Plates need to match, knives need to look straight. He doesn't like mess. He's a completist. This could be the result of his feelings of being out of control elsewhere in his life - the bigger picture perhaps. Maybe he feels emasculated by being a 'blogger boyfriend' with no real purpose of his own?
She seems to be developing a pattern of compensatory behaviour with him - she knows when to shut him up by distracting him with the dogs. She indulges him in his cooking and organising when she needs new 'content'. She likes his pretentious food habits "oooh, look at all these scrummy cheeses Char Char got from Daylesford Farm" because it elevates her own self. But then she discards him when he serves no purpose. It's really sad to see, for both for them.
Caveat: I am not trying to excuse Charlie's behaviour, I suppose I just wonder why the hell they are together.
I agree with your first 3 paragraphs. I think Charlie could have a touch of Asperger's. Obviously he is high functioning but he has never held a job down for very long or made a success of anything.
When I used to watch them in the London house, I had thoughts of I wouldn't mind a man like that if I could gag him! He did absolutely everything in the house she didn't do anything except the odd mac and cheese or an AD for the Thermomix.
Her filming room was a mess, I remember her showing her makeup unit. The dust and grime had me take a breath. Simply put I think she is lazy and unorganised and she relies on Charlie.
Charlie also appears to have been brought up with 2 very overpowering women. Maybe, when he gets the opportunity to talk he doesn't know when to stop and he talks fast, maybe before he is shut down.
Why are they still together? I haven't a clue. There appears to be some affection on his behalf but not hers. She could be putting on some cool, aloof persona but even William and Kate manage to show some affection on official events through looks and smiles.
She is still planning the wedding so there must be some love there.
If it is true that he hasnt contributed financially to the new house, then it has to be true love. I can't see Josie or her mum letting him come along unless one or both of them are getting something out of it. Whatever that something is. Charlie comes from a wealthy family we don't know what they contributed now or in the past.
Both families come across as ruthless.
I think Charlie has found his calling or purpose in life, in the Cotswolds, Josie not so much. I think he will make contacts quicker than her, to be a know it all you have to ask questions and feign an interest. He can do that. Josie just libels the local farmer.
After all that rambling I still haven't figured out why they are together and why she puts up with his tantrums. When/if they have children it will only get worse.