6) Sweet food is best paired with a wine that is slightly less sweet.
Sweetness in food decreases both wine’s fruit flavors and some of the sweetness in the wine. Sweet foods can make the wine taste tart or even sour — unless the wine has some sweetness of its own.
If you want to pair a dessert wedding cake with a Champagne, you would choose an extra dry or demi sec/semi-sweet sparkling wine because the cake sugar needs to have some sugar in the wine to match it. A dry (brut, brut nature, extra brut) Champagne would be out of balance with a sweet cake.
The reason you pair a sweet dessert with slightly less sweet wine is that it is easy to overwhelm the sweet taste buds and make everything out of balance toward sweetness which some would call a “cloying” taste.