A 57-year-old woman in Encinitas, Calif., recently rediscovered a male coworker from a job she left six months ago. Divorced since 1984, she's been in a committed relationship since 2002. But when this "pudgy, brilliant guy" from her past sent her a friend request, she accepted at once. "I remembered how he made me laugh harder than anyone else," she explains. "He was someone with whom I found myself effortlessly sharing stories about my ex-husband, my frustrations over juggling grandchildren visitations and my disappointments about the man I live with.

See also: Reigniting an old flame. 

"He listened without interruption, then offered some really good advice. Now that we're in a cozy, revived friendship, our challenge is this: How do we navigate our relationship without crossing the line? I love my boyfriend, but he's a really serious person who doesn't like to engage in emotional reflection. This little flirtation gives me an enormous boost."

Indeed, flirty friendships lift us from the malaise that accompanies the grind of ordinary life. They provide an oasis from financial pressures and family stress. We get to remain men and women of mystery — alluring, unconquered, uncomplicated. Yet for all their perks, these liaisons also pose distinct challenges, even dangers.

"A flirty friendship on the side of a committed relationship is healthy only if you set clear boundaries," says psychotherapist Moss, who specializes in counseling couples. "You each need to know you are not going to cross the line, even if the desire is there. It takes a real grownup to achieve this: psychological and spiritual integration, the blending of ego and your integrity."

Keeping an admiring male or female in the platonic category can be particularly trying when a primary relationship hits a maddening turn. Distressed and lonely, we are in a heightened state of vulnerability to new romantic attachments.

Next: Help, I'm fantasizing about my platonic friend. >>