Isn't it remarkable how swiftly lifelong friendships crash and burn when a new spouse does not embrace them? Recently while dining with my friend Klaus, he told me of his best friend Eric who married Jill. For no apparent reason Jill took an intense dislike to Klaus. At first she pretended to approve of her new husband's best buddy, but soon set about dismantling the friendship which had begun at school in another country.

She wasn't even particularly devious. She simply began to no longer invite Klaus for dinner; previously a weekly event. If he popped in to catch-up with Eric, she would glare reproachfully and pointedly snub him. And if the boys had the temerity to meet elsewhere; Jill would sulk. Eventually the strain became too much for Eric. Reviewing his enjoyable history with Klaus and considering the appalling behaviour of his new wife; he took the only sensible decision he could. He dropped his thirty year friendship with Klaus.

As Klaus disconsolately told his tale, my mind wandered to the demise of my erstwhile 'best' friendship. Clive and I travelled and partied in America, Europe and Singapore and indulged in numerous, decadent bonding experiences, (the more decadent, the more bonding). We completed most of South Africa's iconic endurance events like the Comrades and the Duzi canoe race; we played social football and we knew each other's secrets. We were great mates.

Seemingly happily married, Clive was an incorrigible philanderer. Thus, when he confided he was seeing a girl, it never surprised me. It became apparent there was more to the seeing, when he divorced his bewildered wife and married the new girl, despite her being half his age. I was ambivalent about his young lady; immature and moderately attractive, the nicest thing I can say about her is that she was breathtakingly stupid. Interestingly this potentially debilitating attribute, didn't inhibit her from tirelessly providing us with the wisdom of her short life's experiences.

Soon after the wedding, astonishing stories emerged of Clive threatening old friends with violence, pursuant to apparent aspersions cast by them on his lady's integrity. Although the alleged insults were perceived only by her as being insults, this was lost on Clive. I discounted the stories as mere gossip until one night at dinner, she picked a fight with me.

Later as I lay in bed and reflected on the extraordinarily unpleasant turn the evening had taken, I nonetheless assumed I would in due course resolve matters with Clive. It was not to be. He decided to exclude me from his life. Reluctantly I attributed it to the mysterious consequences of an older man falling in love with a nymphet; and moved on.

Unlike Klaus I have never discussed the 'loss' of my friend. But as I listened to his tale about Eric and Jill, I experienced mounting relief when I realized my circumstances were not unique and, not necessarily as I had assumed, my fault. I decided to explore why these situations arise and how they can be dealt with.

I spoke to Vanessa Gaydon, a psychologist currently doing her doctorate. "If one looks at it analytically it can be traced back to the oedipal complex. In life we have to master being on the periphery while moving in and out of relationships of more than two, the original relationship with the mother. Instinct is to push the third out, literally to kill them off. Thus when we experience being the third, there is a wish to retaliate; in the oedipal complex, to kill the parent. Basically 'three's a crowd'."

She continued a little less technically. "The issue of threes in relationships occurs throughout life - infant and parents; child parent and sibling; friends at school; spouse and family and then spouse and best friend. Always, if we are the third member of the threesome, we are at risk of being annihilated, so we attempt to annihilate the threat." Evidently I was a threat to Clive's young wife. I had been around longer and so, according to Vanessa's analysis, I was up for annihilation. Scary stuff psychology!

"Looking at your case with Clive - it is clear you bonded and shared experiences that excluded her, which put her on the periphery of the triangle. To add to this, she probably sensed your disapproval. Her immaturity meant she was unable to develop any real insight to the situation, so she began to fight for her place."

It was quite uncanny how succinctly and precisely she summarised the situation; but what to do about it?

"When a person chooses a new partner, they are entitled to a more important position in the triangle so it becomes necessary for the other member to shift to the periphery. It does not mean the relationship should end. Take the example of the dreaded 'mother in law'. She has to learn that the 'child' no longer belongs to her and she has to move out of the closely bonded relationship, to make space for the spouse." It seemed so obvious.

"It helps to talk to the other parties. Hopefully then all three can be reassured there is space (just a different space), for everyone. So in short you should have spoken to Clive and told him how you felt."

"I would have, but he slammed the phone down on me", I thought petulantly. Vanessa concluded, "Perhaps you should also have gently spoken to her." Much as I endorsed and accepted what Vanessa said, the reality of following her advice was a bit more complex. The fiasco with Clive and his wife began so emotionally and explosively; 'gently' speaking to either of them had never been an option.

I then talked to practising psychologist Dr Nick Christodolou. His first observation was that with regard to Clive's new wife, "You were part of the deceit, which is why she needs to get rid of you".

"Sorry, but I'm not with you - deceit?"

"Yes. You knew Clive was philandering with her, but you never informed his wife. So you were part of the deceit. Now if he philanders again; which could and probably will happen, given that he cheated on his wife with the new girl, you will be on his side. You won't tell his new young wife." It made uncomfortable sense.

"The other thing is that because of your 'bonding' experiences, you and Clive have 'in' jokes and you talk and laugh at things that never involved her. So when you reminisce, her mind exaggerates the incidents to much more than they actually were and she sees you as having a better relationship with him than she does. So you must go". My recurrent, proposed elimination was getting irksome.

He then observed en passant that I was behaving a bit like her. Early on I had decided she was stupid, probably to some extent subjectively, so as to push out the 'third' member who threatened my relationship. Damn! I preferred things when they were all her fault.

What depressed me most was that it was so typical. Our situation was a text book case. I always thought Clive and I were different and thus, if I ever considered it, not prone to classic psychological syndromes. But obviously, like everybody else, we were.

I asked Dr Christodolou what could now be done about it. "Unfortunately you are going to have to accept that it is all over. Think of people who say, 'we are not lovers anymore, let's just be friends.' That is a basic lie; it is never going to come about; because at that point, the relationship has already disintegrated. Until you attend the funeral of the party objecting to your continued existence in the friendship, you have no chance of resurrecting it." Brutal stuff psychology!

It seems that the best way of dealing with the arrival of a third party in a relationship, in whatever context, is to be on the look-out for warning signs of possible tension. Like sulking, gratuitous rudeness, exaggerated lack of interest in what is being discussed or trouble making. If they surface, then prudently withdraw from the set-up, for a while at least. Once things calm down, talk to the aggrieved party and make a point of reassuring them they are welcome. Include them in your life. Don't dwell on periods when they weren't part of the scene - don't reminisce, which automatically excludes them. And lastly, refrain from ‘in' jokes, which intellectually exclude anyone not party to them. Rather try and create new ones they can be part of.

In my case, short of taking out a contract on Clive's nymphet, or regularly scanning the obituary columns with my fingers crossed, it seems there is not much I can do. Sadly, if I had known then what I know now, the breakdown might never have occurred; regrettably a sentiment that resonates in most heartbreaking situations which could have been avoided.