Has trade beetween two countries ever ended, even momentarily, due to a change in their trade relations?
Yes indeed. Many nation and empires ended trade between one another for many reasons. Whether it be because of war, disputes between border positions, even over religion. Trade is necessary for any nation to grow and prosper for self goals and for friend connections to other nations. The Venetians are a good example of this.
The City of Venice was built for over seas trade because the whole city is basically a water port! And because of this, along with the fact that they were the masters of ship building, they became a European power house in trade in the Mediteranian. One of the biggest nation they traded with was the Ottoman Empire. They benefited greatly from eachother, The Venetians obtained spices and other riches from the Middle East and Asian areas, while the Ottomans got a combination of boats, weaponry, and food. However, this was temporarily halted during the era of Crusades. Europeans wanted no trade between the Middle Eastern Muslim people because they were wanting to take control over the Holy Land. Since Venice was in Europe, that ment no trade for them, however, they quickly got around it.