I shall work up some stats in due course, but what strikes me immediately is that women's health has improved over the last century. Every president since Harding has been married throughout his term in office. But of earlier presidents, Thomas Jefferson, Andrew Jackson, Martin Van Buren and Chester A. Arthur had in fact become widowers before becoming president, and John Tyler, Benjamin Harrison and Woodrow Wilson all lost their wives during their terms in office (Tyler and Wilson married again while in the White House; Harrison's wife died the week before the 1892 election, which he lost). James Buchanan and Grover Cleveland both came to the White House as bachelors, though Cleveland married during his first term (Buchanan, by most accounts, not being the marrying kind). Only one president has ever been divorced, but that was thirty years before he became president (and he had remarried in the meantime).
As with presidents, there has only been one Vice-President in the twentieth century who was a widower during his term of office - Charles Curtis (1929-33). In earlier days, several of the same names crop up: Jefferson served as Vice-President under John Adams from 1797 to 1801; he and both of his own Vice-Presidents, Aaron Burr (1801-05) and George Clinton (1805-12), were widowers (though Burr married again much later in life). So were Martin Van Buren (1832-36), William Wheeler (1877-81), and Chester A. Arthur (a bit later in 1881). (John Tyler, of course, does not go on this list as his wife was still alive during the month that he was Vice-President). William Rufus King (also Vice-President for a month, in 1853) was, like his good friend James Buchanan, not the marrying kind. Richard Mentor Johnson (1837-1841) was not legally married but lived openly with a slave woman, Julia Chinn, a relationship which cost him the electoral college vote in 1836 (though the Senate voted him in in the end). Poor Julia was three years dead by then, but it still made a difference to the Virginia electors.
Thanks for the idea, applez. I'm very conscious that I haven't really met your challenge; I need to actually look at the lives and lifespans of the women concerned, rather than just identifying them by their husbands' names! So please take this as a first step towards a more informative later post. I would not be at all surprised to find a fairly sharp gap between the average lifespans of the wives of presidents and vice-presidents depending on whether they lived through the medical revolution of the late 19th century or not.