Women who love sociopaths

In response to the previous post about Dominique Strauss-Kahn, a Slate article about his wife and other women who love socipaths:

Why have Catherine Greig, the girlfriend of mobster Whitey Bulger, and Anne Sinclair, the wife of accused rapist Dominique Strauss-Kahn, stood by their men? I’m going to play amateur psychiatrist and declare both men appear to be sociopaths. There’s not much doubt with Bulger, who is allegedly behind at least 19 murders and even by the standards of professional criminals was considered to be particularly vicious. Granted, Strauss-Kahn, until his recent indictment on rape charges, was a highly successful international bureaucrat possibly on his way to becoming president of France. Yet his wife surely knew about his obsessive, compulsive philandering. Did she never hear word that the Great Seducer sometimes forced himself on the unwilling? She certainly now knows that the night he spent in the Sofitel he propositioned two female employees, who rebuffed him, before his encounter with the maid. If the press leaks are accurate, his defense against the rape charge may be that the sexual encounter with the woman who came to clean his room was consensual. Yet it is Sinclair’s money which is making his defense possible. Given the costs of his luxurious house arrest, his security, his lawyers, his investigators, she could be sinking $1 million a month into trying to clear a husband whose treatment of women is pathological. Sinclair, who has brains, beauty, ambition, and money, stepped aside from her successful career as a journalist to help Strauss-Kahn’s rise. I imagine, now that she is in her 60s, she loathes the idea of a future as an aging single woman, left off the guest list for the best parties. But at what point do you stop defending the indefensible?

What does that even mean? Is there some objective definition of what qualifies behavior as "indefensible"? I mean, if they're into their wayward partners, that's their choice, right?