Mrs. Plant is trying a new sauce, and it is too sweet for her taste.
What can we do about it?
Need answer fast! 
Add a can of tomato puree or crushed tomatoes (NOT tomato paste, which is very sweet), a bunch of salt/pepper, whatever herbs you like in sauce (oregano, basil, etc) and some sauteed onions and garlic.
Basically you’re diluting the sugar then adding strong and salty flavors.
Add an equal (or “to taste”) amount of the original sauce, minus the sweeteners.
Thanks, Hello Again!
If I may piggyback:
I cooked up some sauce from tomatoes I froze in summer. It is nice and thick, but it’s too sweet. Same suggestions?
What I was thinking. Double the recipe, omit whatever is sweet.
Try a bit of red wine vinegar.
what was the name of the sauce as hubby likes the sweet stuff as I added sugar tonight to the spaghetti sauce …
That is odd. Tomatoes are acidic, not sweet. I have made sauce from minced fresh tomatoes, the recipe from a Nero Wolfe novel, and it was not at all sweet. Perhaps freezing creates some sugars.
Tomatoes, though acidic, have inherent sugars; some varieties more than others.
Let’s work backwards. Chile heat can be counteracted with sugar; that’s how they grade the Scovill scores. Maybe you could counteract sweetness with heat.
However, this might be one of those things that only appears to make sense.