So I wasn't entirely shocked at John Edwards' admission that he'd had an affair in 2006. Mostly, I was relieved that Elizabeth Edwards wasn't standing by his side on television. Maybe everyone learned from the sad spectacle of Silda Spitzer that the straying mate only looks worse when the spouse appears beside him while he makes his confession.

While most of the non-tabloid media attention has focused on how Edwards' disclosure might affect the presidential race, I've been obsessing instead on the connections between cancer, survivorship, sexuality, and relationships.

Now, I don't know anything about the Edwards' marriage. I believe that all marriages are deep mysteries - often enough to the partners themselves, and certainly to the outside world. I do know something about the aftermath of cancer, however, and the still-taboo topic of how it can affect a marriage or other committed relationship.

The facts, as we know them so far, are that John Edwards had an affair in 2006 with a video producer for his campaign, Rielle Hunter. He has specifically said it occurred at a time when Elizabeth's cancer was in remission. It ended well before she was diagnosed with a recurrence in March of 2007. He confessed to her back in 2006 and asked her forgiveness. She decided to stay in the marriage.

What follows is informed speculation. It's based on a mixture of my own experiences as a spouse of a two-time cancer survivor (a term my husband and I both dislike, because it falsely implies the experience is finite) and those of other couples who've dealt with cancer. In the interest of everyone's privacy, I've blurred some of my experiences with those of others.

For most couples going through cancer, the diagnosis and immediate treatment are a time of solidarity. The healthy partner supports and cares for his or her partner during chemo or radiation or recovery from surgery - or some combination of the above. The sick partner rallies to the extent physically possible and is grateful for support from every quarter, but especially from the caretaking spouse. You each marvel at the others' strength, and you're grateful that you have each other. (I realize a few spouses totally freak out, but I'm pretty confident that most react by drawing on their better angels.)

Then, abruptly, treatment ends. And you have to figure out how to rebuild your lives, and how to be a "normal" couple again. Nobody warns you about this. There's no roadmap. You might not even realize you're still on a major journey until you're already lost deep in the woods. No wonder lots of people's relationships founder.

Here are some of the ways the survivor can react. He or she can pretend everything is okay, which is right in line with the cultural script, but is bound to fail. He or she might fall into deep depression. Or act positively manic. Or be paralyzed with anxiety. Or try to make up for lost time by acting like a teenager. Or dwell obsessively on every bodily twinge. Or go on a fitness kick. Or any combination of the above, plus a whole kaleidescope of other possible reactions.

Through all of this, the overwhelming cultural message is very simple: You should be deeply grateful to be alive. There's very little legitimate space for anger and grief and depression.

The post-treatment process of coping and rebuilding and grieving is more complicated, of course, if treatment has affected the person's sexuality. That's perhaps obvious for breast or uterine or prostate cancers. But chemotherapy often has medium-to-long-term effects on hormone levels and libido. Surgery and scars can lead to feelings of unattractiveness. I know of numerous couples who've split up in the aftermath of breast or prostate cancer. I've heard anecdotally of prostate cancer survivors who became so depressed about their sexual losses that they took their own lives. So much for survivorship.

What's more, any form of cancer can result in profound alienation from one's own body. If your cells have risen up against you, how can you trust your own flesh? How can you revel in it again? And if you do find a way back to pleasure, will you still include your partner in it?

(That last question goes back to a woman I knew who'd had surgery for breast cancer, then got reconstructive surgery several years later. She was thrilled with her new shape. Soon thereafter she divorced her husband of 20 years. I don't know exactly what happened between them - they'd also spent years living in a trailer while building a house with their own hands - but clearly her "new" body played some role as a catalyst.)

The "healthy" partner, too, has to readjust, though he or she may not even realize this. Speaking for myself, I was so invested in the idea that I couldn't burden my husband with mundane frustrations that I bottled up a lot of resentments, and I had to learn again that he was strong enough to be an equal partner - that I didn't have to "protect" him constantly. I'm pretty sure there are lots of variations on these themes, too.

Both partners may be just sick to death of sickness. And that's the first thing my husband said when I mentioned John Edwards' confession. He said, maybe Edwards had an affair because he just wanted things to be normal again. Maybe he was tired of cancer and treatment.

My first thought was that maybe one or both of them just couldn't see a way to reconnect erotically after breast cancer. Speaking only for myself again, when I had a scare with an unclear mammogram - one that took months to clear up - I felt profoundly alienated from my body as a source of pleasure. And I didn't even have cancer, just a bad case of paranoia!

Maybe having an affair when your spouse has just faced down mortality is a way of affirming your own survival. Maybe it's a form of denial about your partner's mortality, and your own. This might be just an extension of the stereotypical mid-life crisis - but cranked up to eleven.

And maybe, with the pressures of raising two young kids and running for president the Edwards just hadn't yet figured out how to be a couple together again. My husband and I struggled enough, and we only had two little kids and a couple of university jobs.

In the end, why John Edwards strayed will remain a mystery to everyone outside his family, and that's only right. They deserve their privacy. Elizabeth has asked for privacy as they work through this. A marriage should remain a mystery to everyone outside it.

And yet, while he publicly said he had an affair because he'd grown selfish while campaigning, I think his motivations must be more complex. No one comes through cancer treatment unscathed. Not the patient, and not his or her partner.

With this in mind, I don't think you have to approve of his actions to acknowledge that both he and Elizabeth were under tremendous pressure, and that his affair might be at least partly a reaction to their cancer crisis. That doesn't mean it was right. It's even possible he's just a horndog on the Bill Clinton model - though my gut feeling is that he's not. (That assessment would have to change if he in fact spent the night with Hunter at the hotel where the National Enquirer shot that incriminating photo - in 2008, not 2006. We still don't know all the facts.)

I just think there's way more room here for compassion than for judgment. Maybe John Edwards was trying to make excuses for himself when he pointed out that Elizabeth was in remission at the time of his affair. At the same time, his comment ought to be a reminder that cancer messes with your mind, whether it's you or your partner who's got it, and otherwise sensible people might behave more foolishly as they muddle through the post-treatment trauma.

Finally, I think this news may illuminate why Elizabeth Edwards decided to stay on the campaign trail after her recurrence was diagnosed, and why she seemed to arrive at her decision so quickly. As the AP reports:

In a statement last night, Elizabeth Edwards said that after a "long and painful process" she decided to stand by her husband. Mrs. Edwards called the affair a "terrible mistake" but said the healing process was "oddly made somewhat easier" after her diagnosis of a reoccurrence of breast cancer in March 2007.

First, it sounds to me very much as though the new diagnosis put the Edwards back into the "let's fight this beast together" mode. I can easily imagine that the need for togetherness would help overcome the hurt and fury that Elizabeth was clearly still feeling.

And second, Elizabeth had already decided to stick with John after he'd disappointed her. Cancer, at least, is impersonal in its cruelty. Having forgiven her husband for his deliberate actions, Elizabeth had already cast her lot with him. I can totally understand why she wouldn't let cruel but impersonal fate affect her loyalty.

This is a lightly edited reprint of a post that originally appeared at my blog, Kittywampus.