He kicked the cigarette habit, but you can’t. It’s a vicious cycle: You smoke, he complains, you fight, you stress, and then you need to smoke again. (Although correlation isn’t causation; there are other risk factors too.) A group at the Centre for Economic Policy Research in Australia found that smoking was not a very high risk factor in a marriage if both couples are smokers. But divorce rates increase significantly—76-95 percent higher—when only one spouse (especially the wife) has the habit. Quitting saves your (love) life.