*If you anthropomorphise him, he looks quite happy here but actually he's just an animal who's been running and has his mouth open.
Barry is reassessing his situation and finding it not entirely to his liking. It is hardly surprising. Charlie and he did not often see eye to eye (she was generally a bit of a curmudgeon - even when young - and he was always too juvenile with very different lifestyle interests to hers) but they were always together, probably about 23.5 hours out of every 24, for all but the first couple of months of his three year existence. She was never really a parent figure but she was pack leader (that situation was renegotiated somewhat in the last few weeks of her life) and he respected that, more or less, despite being much, much bigger than her.
So, he is getting used to her not being here, but he doesn't like it and while it would be going too far to say it's like losing a limb - because he has all the limbs he needs - it's certainly losing something. Yesterday morning, for instance, he was all about going out the back - coming in - going out and each time it was as though he was expecting to see Charlie there, which would of course be the normal circumstance. Now, there's no-one for him except his people (he has also shown a much greater interest in the cats, which is strange). Yesterday morning I took him up to the park for a brief walk and we ran into Joan and her ancient Chock, who Charlie always used to bark at so Barry has never really spent time with. He and Barry had a kind of silent commune, most of which was Barry sniffing Chock's arse (Joan said he'd just had his anal glands 'done' and demonstrated to me the size of one of them and said she'd never seen anything like it). Ah, the world of dogs. The spectrum of fascinating can so quickly go into the realm of disgusting.
23 July update: He seems to be adjusting better, and perhaps to some degree enjoying his solo status - I hope he doesn't enjoy it too much as Ferdinand will be here in ten days and then change will be absolute. The challenge then will be to stop Barry feeling on the outer (I think to say he was jealous when Charlie got attention is too much projection; more likely, he was thinking, 'attention is on offer, I need to get some of that action'. Or who knows. But I don't know that he really enjoys his walks as much when it's just him alone; Charlie and Barry had a special walking system, of drawing each other's attention to interesting smells, activities etc and they could be a very effective pair of satellites to the walking human, whereas Barry has to just pay attention to the walking human who he probably finds a little dull.