Hard to tell what’s causing this. The biological explanation could be something related to the grandmother hypothesis, but the evidence is far from conclusive. Basically what it says, is that female longevity is an adaptation where postmenopausal women can contribute to the survival of their grandchildren. Who knows.
What is more likely to be the cause, though, is women’s overall behaviour during their lives—which, BTW, also has biological basis. (A “lifestyle choice” is not really a choice.) Women are more likely (and faster) than men to see a doctor when they suspect a medical problem and they are less likely to take chances, resulting in men having a better chance of dying in accidents. Men are, for example, twice as likely to get killed in a car crash and a lot more likely to get killed in a war or to be murdered.