The illegal option

If Governor Spitzer wanted to have sex with a younger woman then instead of hiring a prostitute he could have gotten a divorce and remarried, just like so many other rich and powerful men. Or he could have had an affair. Of these options hiring a prostitute is the least threatening to marriage but it's the only option which is illegal. In contrast, getting a divorce and remarrying a younger woman is so common it doesn't even stop a man from running for President.

Alex Tabarrok, "Trade-Offs," Marginal Revolution