My OH does have "his" money - sort of. He inherited a reasonable whack when his dad died, which sits in a joint account. I say it's "his" money because it was left to him, (although, legally it's ours, I guess) and I don't think it's fair for me to spend it without asking him, but he's never once refused. That said, it mostly sits there, but we've used it for a couple of bigger purchases that we would make joint decisions on anyway, but when he was away on a work course a while ago, I asked him first before replacing the packed-up dishwasher, but I think that's normal.
His wages go into the joint account- he's rubbish at remembering to pay things, and he earns much more than I do, so it makes sense. He also went though a stage many years ago where he couldn't control his spending (he was depressed for a while).
He pays for school uniform, childminder etc, purely because I don't earn enough.
My wages and the CB go into my own account, I use it for day to day stuff, days out, pocket money, lunches, clubs etc but if I need more, I just use the joint account.
I personally would worry if £4 caused him that much of an issue - if you can afford to save £300 a month, you're obviously not struggling for every penny so there must be another reason, maybe the problem is with him.