Whose fault is infidelity?

The most deeply despised player in an affair tends not to be the cheating husband, but the object of his newfound affection: the lady behind the lipstick on the collar.

What is it about these women that lure away committed men? What is it like to be them, and what is it like on the hopeless other end, trying to silence their siren calls?

A series of essays collected in "The Other Woman," edited by "The Bone Weaver" author Victoria Zackheim, explores the complex mysteries of the modern-day mistress from both female points of the triangle. (Nobody cares what the men are thinking because the assumption is they're not.)

Canadian TV personality Mary Jo Eustace is a left-behind wife. Her mate runs off with actress Tori Spelling. This is not made up.

"And just when I thought I couldn't feel any more pain, he says, 'I don't love you anymore. And I don't respect you', " Eustace writes in her essay "Palm Spring."

"He takes a breath. 'I haven't for a very long time.' "

In editor Zackheim's own piece, she is the mistress, madly in love with a married man, and ultimately the loser in the game.

"It troubled me that I understood something he could not: that despite his anger toward her, he was unable — perhaps would never be able — to disengage from their sacred bonds of marriage," Zackheim laments in "Phantom Wife."

The authors reveal a rich collection of personal sagas, the kind that women tell each other over Cosmos after sobbing in private has passed, and everybody is ready to have a good laugh and see things with clarity.

It might not be the thing you buy for a newly devastated friend.

One has to be careful with writers telling their own stories; the tales often sound more bearable, or at least more sexy, than they actually are, because writers have an out: They can turn their pain into art; even during tears, they are putting words to their woe.

In the strongest piece of the bunch, seasoned novelist Caroline Leavitt writes with a storyteller's nose for suspense and conflict in the unbelievable true-life tale "Cassandra." With a sordid, tangled plot involving shrink idolization, mental illness, lies within lies and other hairpin turns of love and betrayal, it ventures way beyond the fundamental scandal of infidelity at the root of each essay.

The selection is varied enough not to get stale, and generously circumvents common stereotypes expected from the weepy women genre, even though there's an obvious self-indulgence to this kind of literary assignment.

There's a noble — if not entirely necessary — effort to include the unconventional.

Two stories involve lesbian affairs, but the most striking inclusion is "The Man With the Big Hands," which significantly diminishes the evilness of every other man in the book by introducing a child-molesting uncle.

"I became the other woman at six," writes Maxinne Rhea Leighton.

Gulp. What is everybody else whining about?

That's not entirely fair; this book rarely whines. It's noticeably grounded, in fact.

"There's all sorts of temptation around each of us, all the time," reasons award-winning writer Diana Abu-Jaber in "The Lost City of Love."

"But, for better or worse, I guess I'm oriented toward a single focus: the selfish pleasure of trying to spend a lifetime with one person."

That sure sounds good on paper. But in some of these stories, so does being the illicit lover of a tormented, noncommittal married man.