There's something called Married Couples Allowance which applies in your situation provided one of you was born before 6th April 1935. Allegedly it reduces your tax bill by between £314 and £816 in the current year, depending on pension and other income. There's a calculator online if the Google the above phrase and go to the gov.uk website.
Government has assessed people as individuals for tax purposes, rather than using the old married man's tax allowance for donkeys years now. It is rather down to the individual to ensure that each in a marriage/relationship has enough in savings or pension income to maximise this opportunity. I assume you have put every scrap of non-ISA held savings in your wife's name to maximise the use of this.