As the case against Philip Markoff, "the Craigslist Killer," becomes ever-more-common knowledge, Megan McAllister, his fiancée, continues to publicly defend him.

On April 21 she said: "He could not hurt a fly…Philip is a beautiful person, inside and out."

And two days ago: "What has been portrayed and leaked to the media is not the Philip Markoff that I know. To me and my family, he is a loving and caring person."

Could it be? Maybe a huge mistake has been made. Maybe Markoff is just a regular guy who got pounced upon by a sensation-hungry public. He'll win in court, and the two of them will get married in an avalanche of bliss. Then they will live happily after.

But probably that's not going to happen.

(In case you haven't heard yet, Markoff is the medical school student who has been charged with killing one woman and robbing and kidnapping another. He allegedly lured both women through ads they posted on Craigslist, and the evidence against him is formidable.)

What is this fiancée thinking?

I think she is not thinking at all. Her thinking powers have been preempted by blind loyalty. It's a beautiful thing, actually. And it happens to all of us. At some point in our lives, whether consciously or unconsciously, we pick teams. Often our teams consist of people who just happened to land in our lives: family members we grew up with, friends we met through random encounters. And then, more or less, we don't think about whether those people should stay picked or not. (Before Facebook hit the scene, "de-friend" wasn't even a word.) On the whole, blind loyalty is probably good for civilization.

Loyalty is beautiful, and good for many things. But it is not good for distinguishing fact from fiction. Or for distinguishing fiancés who should be married from fiancés who should not. The case of Megan McAllister is a drama of misplaced loyalty.

As irrational as she looks to the rest of us, we are just as irrational much of the time. The only difference is, the people we are defending so stalwartly are usually ourselves.

For example, have you ever heard of the "Lake Woebegone effect"? This common illusion explains why, according to Wikipedia, "Swedish researcher Ola Svenson found that 88% of American college students rated themselves as above the median on driving skills."

It seems to be built into human nature. We tend to believe we're nice people even if we just slammed the phone down on someone, that we're caring people even if we just walked right by someone needing our help, and honest even if we just told a little white lie.

Add to the list of things loyalty is not good for: Distinguishing the things we excel at from the things we actually don't.

That's why, in our quests for personal excellence, we sometimes need to get some outside help. Overwhelmed with blind and sincere loyalty to ourselves, we may not be able to accurately gauge our own failings and triumphs. But other people can. Our Sages advise: "Assume for yourself a master, acquire for yourself a friend" (Ethics of the Fathers, 1:6). In other words, for optimal spiritual growth, get a mentor and a buddy.