Any ideas please
More information would have helped. There are many possible reasons. The nature or size of the item could make it too costly, unsuitable or prohibited for international delivery. What does the seller's postal policy state? The fact that one seller made an exception in your case doesn't mean that others will.
It won't be surprising of more sellers withdraw from overseas delivery when they understand the risks. If a buyer finds fault with an item the seller may now be required not only to refund in full, but also to take full responsibility for the return delivery. I doubt whether sellers who have had to let buyers keep their items for nothing because of the cost and difficulty of arranging returns from another country will be quick to post abroad again.