Earlier quoted context omitted.
I'll take "things you can do when you're single"... can't quite imagine sidling up to significant other with the gambit "Darling, would you mind terribly if I spent £1000 on Kazakhstani emoji domains?"
A common wallet with a SO freaks me out :)
Having an account just for expenses, with no overdraft, that's usually at $0.00 balance is useful for other purposes too (ACH pull is dangerous! Especially when everyone who has ever looked at your check can do it)