Editor’s note: Jane Ganahl is the author of the memoir Naked on the Page: The Misadventures of My Unmarried Midlife and editor of the anthology Single Woman of a Certain Age. For five years she penned the acclaimed Sunday column, Single Minded, for the San Francisco Chronicle, which earned her a place in MSN’s Singles Hall of Fame. 

When "The Good Wife" premieres on CBS September 22, I can promise you that viewers will be mostly concerned with Julianna Margulies’ character: the humiliated wife of yet another powerful politico who could not keep his vices – and his hands – to himself. But I can also promise you that while most viewers will focus on the struggles of Margulies’ "good wife," I’ll be scouring the show for more prurient details on "the other woman."

Who was she? What was so powerful about this attraction that made this famous man risk everything? Was she pretty? Smart?

I’m not proud of this reaction, but I’m evidently not alone. When South Carolina governor Mark Sanford joined a rogue gallery of powerful men (including Pres. Bill Clinton, New York governor Eliot Spitzer, presidential hopefuls John Edwards and Gary Hart) and confessed that he’d flown half a world away to see a woman he considered his "soul mate," Maria Belen Chapur was immediately one of the top searches on the Web.

It turns out she is neither a vamp, nor a 20-something aide with ruthless ambition. Chapur is 43, and described as a highly intelligent, high-powered international businesswoman, and a single mother of two. Pretty, yes, but pretty often has nothing to do with it.

Whether a woman becomes The Other Woman is 90 percent about timing. When a man’s marital unhappiness opens a door to infidelity, if you’re standing on the other side of the door and have unmet needs of your own, it can happen with alarming ease.

At least this was the case in my own life.

I was a sickly shade of blue after my second divorce, facing 40 and feeling bitter about relationships. A sympathetic work colleague, upon whose broad shoulders I cried, confided in me about his loveless, sexless marriage. And just like that, during a lunch date, he became my lover. When he visited, he always brought expensive champagne and roses. We got drunk on Sunday afternoons and had sex until we passed out. He told someone whose husband never paid her compliments that she was gorgeous. He watered this dead flower and made it bloom again.

It was, in short, the most romantic, perfect relationship I’d ever had. Except for that one teeny-weeny problem of his — being married. It meant we were lying to everyone and sneaking around. But it’s OK, I thought, this is love and someday we’ll be together. Someday he’ll leave the angry, distant wife and be with me, and this will all have been worth it.

After several blissful months, I went to an event he was producing, intent on giving him a joyful surprise visit. Instead, I was stopped in my tracks by the sight of her. She was wearing a peasant skirt and straw hat, and was smiling, dancing and looking warm and funny and lovely. She had her arm around his shoulder. I thought I would die on the spot, imploding in a morass of anger, remorse – and guilt. I had become The Other Woman. Like Madame Bovary, minus the arsenic. Like Glenn Close in "Fatal Attraction," minus the corkscrew curls and the livestock required to make a bunny stew.

Like Glenn’s character (though I left the kitchen knives in the drawer), I confronted him about our future. "What future?" was his wide-eyed reply. That was all I needed to hear, and I ended it quickly. For months, if not years, I felt like I was wearing a scarlet A on my chest, and eyed with suspicion every over-affectionate male slobbering on his companion. I wonder if she’s his Other Woman?

Statistics were in my favor: according to the Journal of Couple and Relationship Therapy, 50 to 60% of all married men cheat at some point in their marriages. That must mean there are millions of Other Women out there ready to play the role. For most — I would guess 90% — it ends badly. But for a few, it pays off handsomely.

We’ve seen Other Women in our culture be transformed into celebrities, leaving marital chaos in their smiling wake. Monica Lewinsky got her own reality TV show after her affair with President Bill Clinton, Ashley Alexandra Dupre made perhaps a million dollars off downloads of her music following her role in the Spitzer drama, and Donna Rice became a national spokeswoman for No Excuses jeans.

Every married woman fears this Other Woman, but who is she?