Has it occurred to you OP that hes a bit of a wanker? That's how he comes across to me. He knows somewhere that the fact he no longer wants to be your partner is goong to cause you huge pain and upset and upheaval to the children too. And will thus cause him both guilt and inconvenience. Not to mention dent his reputation as Mr Wonderful Sensitive New Man. So he has woven an alternative fantasy scenario in his head whereby there is minimal change to anything apartfrom that o e huge thing, and he has talked a blue streak into convincing himself that you can be fine with it, and problem solved, bullet dodged.
You're not fine with it, you couldn't possibly be and you have told him veey clearly you aren't.
So what is happening with all the walks on the beach and evening s with the telly and him saying you're the most wonderful person ever in the world?
HE gets to kid himself his fantasy "solution" will work
YOU get to kid yourself he might change his mind.
You are both utterly deluded. At least we know he is, because this is not fine in any way for you. I think it is highly likely you are too. He is not hanging around being nice out of 'being close to changing his mind'- ness IMO. He is doing it out of cowardice and guilt.
And knowing what he knows about your feelings, it is actually pretty cruel, and extremely selfish.
But like I said, he's a bit of a wanker, isn't he, so that's par for the course.