And why adultery matters.
Marriage, among other things, is a legal contract between two people. A contract that can be terminated by either party at any time. Adultery is a breach of that contract. It matters politically since it is (again, among other things) a breach of contract, arguably the most important contract anyone ever into into. Marriage is, by design, not a private matter.
If someone breaks a contract with someone he or she knows quite well, and at least at one point cared deeply about, shouldn’t that factor into one’s decision on who to elect president? Especially in our current age when presidents have enormous discretionary power and can make people disappear unilaterally?
The analogy I use in these situations is: suppose someone defaults on a car loan, does that affect the likelihood that they will default on a mortgage?
And yes, McCain’s adultery was equally horrible, and an equal sign of low character and trustworthiness.