I would add Verses - located in a former church with high end food. I also like Bhima's Warung. They have fabulous south east asian food that's great for sharing. This is our go to restaurant when we want good food with a romantic atmosphere.
262 King St N, Waterloo, ON N2J2Y9, CA
182 Victoria St N, Kitchener, ON N2H5C6, CA
Depends on your budget but here are a couple that a fancy / romantic:
Langdon Hall (cambridge) - super nice, expensive but worth it
Charcoal / Martinis - a little less fancy and many menu items for varying budgets. They also have Del Dente's downstairs which is yummy italian. This is also romantic and the food is SO good!
Uptown 21 in Waterloo is smaller but great atmosphere. Kind of pricey but not extreme.
Wildcraft - more modern, same owner as Charcoal etc but food is only ok.
Cambridge Mill - new restaurant, very romantic, somewhat pricey but similar to other recommendations. Looks over the grand river so that is a plus also!
Top suggestions are Charcoal, Cambridge Mill and Langdon Hall
425 King Street North, Waterloo, ON n2j 2z5, CA
2980 King St E, Kitchener, ON N2A1A9, CA