NEW YORK (TheStreet) -- Costco (COST) - Get Costco Wholesale Corporation Report  announced last week that it would terminate its partnership with American Express (AXP) - Get American Express Company Report because of high transaction costs. Starting in 2016, American Express will no longer be the exclusive credit card accepted by the retailer.

TheStreet's Jim Cramer says people did not know how important this relationship was. The American Express conference call mentioned Costco, but it turns out the retailer is much more responsible for a lot of the card growth, particularly overseas card growth, than people realized.

The relationship was much more material that people thought, Cramer adds, and the stakes were so high that he wishes they had been telegraphed. The selling has been voluminous, he said, because people were surprised and felt betrayed. 

Must Watch:

TheStreet Recommends

Jim Cramer: Loss of Partnership With Costco Adds to AmEx's Challenges