Did I cook it too hot, too fast?
Did it boil? If so, that may have caused it. What was the ratio of wine to cheese?
When I turned to check on something it did briefly boil. Then I turned it down. What should the ratio be? I think I used one cup wine to 10 oz cheese ( Gruyere and another "stinky" Grueyre cheese
That sounds like a good ratio. The recipe I use is 1 3/4 cups wine to 3/4 lb cheese. It sounds like the boiling caused the curdling. May not look very nice but it probably still tastes ok!