Divorces can be painful, vicious and very expensive. That's the way it's looking in the three-way love triangle between Nisa-Today's, Costcutter and Bibby Line. The constant flirtation of Costcutter has aroused the suspicion and anger of Nisa members for too long, and the buying group's lovelorn battle with its biggest member has looked effectively over from the minute Nisa awarded the combined contract to DHL earlier this month.

In a last, desperate attempt to salvage some value from its affair having lavished gifts on its mistress, Costcutter Bibby Line launched a takeover bid for Nisa earlier this month. The Nisa board, like an old woman scorned, rejected that, too.

Clearly angered, Sir Michael Bibby has now threatened, in a letter to Nisa members, that the Costcutter chain in which his Bibby Line Group has a 51% stake will no longer do business via the buying group, unless a deal is struck. In response, Nisa-Today's chairman Mark Pullen has in effect said: "You can stick your Costcutter business where the sun don't shine."

It's explosive stuff. So the question is: where would a split leave Nisa-Today's and Costcutter? Without question the buying power of both parties would be lessened. Costcutter represents some 40% of sales. And Sir Michael wants his pound of flesh. But the principle on the other side is just as strong. Nisa members want to remain mutual, clinging to the family's roots. It's not just the money £134m is a lot of cash for a shed it's the principle, and all those years of fear, suspicion and hurt.

But what's the end game? Without Nisa, Costcutter has the scale to be more viable than most independents. Without Costcutter, Nisa-Today's could hire a few more members, I suppose, but excepting its plans to grow the symbol group operation, it's Costcutter that accounts for most of Nisa's growth right now. And could a distribution-based business honestly cope if 40% of the volume disappeared overnight?