My friend Liz and I can talk about our hair for hours. She'll tell me if I need to wear a jacket with that certain dress. And we have something only the closest friends have: a Mustache Pact. That means if either of us ever goes into a coma, the other will come and wax the comatose friend. That's a real bud.

Then there are those friendships that require more. Have you ever checked the Caller ID with a moan? Cringed at a lunch invitation? Rolled your eyes when the doorbell rang? If you have a friendship struggle, you're in good company—so to speak. Ethel Mertz had Lucy Ricardo. Barney Rubble had Fred Flintstone. High-maintenance friends pop up in everyone's life at one time or another.

Whether it's because of annoying habits or attitudes, a difficult husband, intolerable children, or overwhelming neediness, sometimes friendship can be tough. A perfect friend? That's annoying, too!

I'd love to become "Super Friend," persevering locomotive–style in those relationships not only when ...