The English poet Lord Byron defined friendship as "love without his wings." But then, he was a guy. To my mind, friends may not fly as passionately close to the sun as lovers, but real friendship does have wings – cooler ones, like a fresh linen towel on your forehead against the dragons of the day. We often talk about the sanctity of marriage, but there's a sanctity in friendship, too. And, like lovers or spouses, old friends can have quarrels that tear them apart.

I know.

Kareen Zebroff and I have been friends for 25 years. We met when she was Canada's yoga star on television, and I was assigned to write a story on her for a national magazine. Over the decades, no one has been more generous, more loving, more ready to help with anything – anything at all, at a moment's notice – than Kareen, through years of assorted euphorias and hours of need. (Example: When my husband and I wanted to sublet our apartment for two months – and because my idea of dusting is to open a window and let the dust blow through – Kareen and five other friends came over and spent five days cleaning it from stem to stern.) Anyway, Kareen (who had written several yoga and cookbooks) decided to write a novel. Over some four years, she talked about it; I listened. Eventually, she read me a chapter, which opened with a small favourite phrase that I frequently use, one involving horrid fascination. Irrationally, unbelievably to me, I felt a nugget of resentment. As she read on, I began to interpret her flirtatiously confiding air, her seemingly supreme confidence, as an attitude of triumph. The kernel of resentment bloomed into full, feverish flower. Kareen must have sensed something was wrong and stopped reading.

During a subsequent evening with friends, Kareen got out her novel and began to read to us. It was very good. Our friends were impressed. Again, unbelievably, I discovered that the gregarious flamboyance I had always loved in my centre-stage friend now seemed to me the blazing one-upmanship of a self-centred egomaniac who, caring nothing about my feelings, was trying to prove that she – not me – was the writer in this group.

"I'm going to be on ‘Charlie Rose,'" said Kareen, somewhat grandiosely, I thought. "I'm going to win the Booker Prize." As waves of resentment billowed through me, I retreated to the bathroom to try to talk myself out of my irrational, competitive and lonely mood. (I'm a grown woman, for God's sake!)

When Kareen called to say her novel was finished, that did it. I blew up, flushing out every, by now highly toxic, resentment toward my unsuspecting friend. It was out-of-body spontaneous combustion. I used to wonder how a person could explode on the stand at his own murder trial when it meant sealing his fate. Now I know.

We had a long and frank talk the next week and told ourselves that the damage had been repaired. It hadn't. Although we didn't talk about it again and remained friends, for the next year and a half the resentment and wariness lurked, like a poisoned mouse behind the refrigerator. Certain subjects – like work – became off-limits. We had gone from sharing everything to being slick, superficial pals with a deep, smouldering grudge.

Such wounds to friendships – from festering misunderstandings to no-holds-barred blowups – are more prevalent than one might think. In most cases the issues are never resolved. In one classic gaffe, my friend Mary Anne inadvertently divulged another friend's confidence to yet another friend. Now her old friend – once her best friend and kindred spirit – is an ex-friend who hasn't spoken to Mary Anne in four years. Mary Anne even flew to her (ex-)friend's winter home in California to explain, but her friend wouldn't even come to the door.

When lovers and spouses get into trouble, they often go for counselling together; friends don't. Maybe they blow apart like Mary Anne & Co.; perhaps they drift into acquaintanceship, occasionally meeting for lunch. Some ignore the problem, hoping it will right itself. But there it waits, the poisoned mouse crouching in the dark.

Nancy deVries, a clinical counsellor in Vancouver, suggests that people don't feel the same kind of pressure to address problems in friendships as they do in spousal relationships. We don't have to live with a friend; we can just drop her. (Drop her? Now there's a sparkling solution. Ten, 20, 25 years of life invested as a friend has just been a waste of time?)

Could it be because the whole idea of friendship is so sacrosanct that we can't bear to even admit that there's a rift? Sometimes, yes. Clair Hawes, a Vancouver psychologist who heads a group of 18 therapists, has this theory: women are supposed to stick together. Part of our history as women, having been largely male dominated, is a great need to stand by one another, and we take pride in doing so. If we can't, we've not only failed ourselves but also let the whole side – our entire gender – down. In most cases, though, I think the concept of getting outside help for our fractured friendships simply never dawns on us.

Fran, for example, gets a divorce, and a valued friend drops out of her life, inexplicably siding with her ex-husband. She can't bring herself to broach the subject. Now, 10 years later, it's too late, though the hurt from the severed friendship is keener than that of the dissolved marriage.

Cheryl is suddenly no longer invited to a longtime friend's dinner parties – is it cavalier thoughtlessness or retribution for some inadvertent slight? Peggy decides to go back to her former lover; an old friend, ferociously judgmental, stops returning her phone calls. Susan goes into business with a friend's brother. The business collapses. Now Susan and her friend are no longer friends.

Wounded feelings fly through the ether, unacknowledged and unchallenged. Without exception, every one of these women said, "It never occurred to me to go for counselling with my friend. It just didn't occur to us."

In her book, Among Friends (McGraw-Hill, 1987), Letty Cottin Pogrebin (who was a founding editor of Ms. magazine) claims that there are 10 basic causes of conflict and warns friends to beware of all of them. Flash points, or danger zones, include one of you getting married or separated, money, competition, dependency and betrayal. When we seek the company of a friend, writes Pogrebin, we do not prepare ourselves for the bad stuff that comes with the good.

When the bad stuff between Kareen and me wouldn't go away, I thought about writing a story about friends getting counselling. Perhaps other friends, I thought, have found themselves at the same kind of impasse with each other. I told Kareen about the idea, momentarily hesitating to suggest that we were prime candidates. "Let's go together," she said.

I phoned at least 30 clinical counsellors listed in the yellow pages to ask if they had ever mediated between two friends. They hadn't and knew of no one who did. But Hawes was so enthusiastic she gathered the 18 therapists in her office together to talk about it. She agreed to meet with Kareen and me.

This experiment – also an experiment for Hawes – to see if professional mediation could help repair a serious rift in an old friendship was one of the most important things I've ever done in my life.

One of the binds we get into, Hawes explained to us in her office, is that while we desperately want to talk about how someone we love – our friend – has pushed our most sensitive buttons, we don't have the language. We may feel resentful because a friend has somehow awakened a long-dormant anxiety or insecurity, but because we can't identify it exactly or it seems petty or silly, we find some side issue to stew over or smoke screen to hide behind. When resentment begins to bubble between friends, they start to separate. They pick on something else: she's too busy or self-centred; she doesn't care about me. The friendship breaks up because of a misunderstanding that never gets resolved.

For me, the eye opener was this explanation from Hawes: whenever we respond in a way that totally surprises us and has nothing to do with logic and we behave as if we are out of control, it is always triggered by something very deep – such as a hurt from childhood.

My resentment and unfathomable outburst could be traced back to my helpless feelings of loss and abandonment at age six, when I lost two people I loved: my mother and my best friend. My mother died; my friend then found a new best friend. The night of Kareen's book reading brought back those memories of being shut out and discarded, of feeling like nobody, nobody at all.

For Kareen, my angry and resentful assault brought back memories of a massive betrayal by her father (too complex to go into here), as well as uneasy recollections of family members negatively attacking other, absent ones. That my outburst had come totally out of the blue, from ill feelings secretly harboured for so long, was, to Kareen, a savage betrayal. When she explained (not for the first time) that her grandiosity simply compensates for its polar opposite – a lack of self-worth – I listened, this time with vast appreciation.

Early in the session, it became clear to us why friends in need, need a mediator. No matter how kindly your friend puts her case, it's hard not to take it personally, and nobody listens when she feels under attack. A counsellor will help you through these moments. When you act defensively, Hawes reminds us, you make the other person your enemy. Throughout the session, our moods – anger, love, gratitude, frustration, mutual resistance – ping-ponged back and forth relentlessly, with Hawes gently guiding us back on track.

Just showing up together is a commitment; you let each other know how much you mean to each other, and "Let's drop the friendship" is not an option. A professional can help you reaffirm your relationship, harking back, as Hawes suggests, to when the two of you first met and had "a knowing" that this was a good person for you. It's true that friends, in a way, do fall in love with each other. And, as with old married couples, the qualities that initially attracted you are the ones that can later drive you to distraction.

When our session with Hawes ended, Kareen and I made a pact. Whenever we feel hurt or angry, we will talk about it immediately, and if we flash in irrational anger, we will know it is based on an old hurt that has nothing to do with each other personally.

An unresolved fight with a friend is like having a hangover: it doesn't matter whether it was Scotch or Sauvignon Blanc – all that matters is that you drank too much. The difference is it may take more than just time to recover. You may even need professional help. It's worth it. In this life, old friends are our radiant hoorays.

Think you and a friend could use some professional help? Try contacting the Canadian Psychological Association at 1-888-472-0657 or click on www.cpa.ca. Another good bet is the Canadian Association of Social Workers; call (613) 729-6668 or check out www.casw-acts.ca.

The professionals you contact may not have experience counselling friends. You may want to ask if they can apply their knowledge of similar issues in other types of relationships to those between friends.