To an economist, the cost of an activity is what you give up to pursue it.
In the year following a divorce, women's living standards fall by 27 percent while men's living standards rise by 10 percent.Steven Landsburg's classic column on Why Men Pay To Stay Married argues that the difference is a compensating differential, the "price" that men pay to women to compensate them for the relatively unpleasant job of marriage.
If men stay in marriages that cost them a lot of money, that just proves they really like being married. They're getting something they value, and they're paying for it.
When I first read this 8 years ago, I thought it was funny. Now, after 19 years of marriage, I wonder why the price is so low.