If Frech food is good, I expect it is, then may I suggest a place called Chez Queux (158 est, rue St-Paul). I'm not a real expert but it was romantic. Location is near the main touristy area (forgot the name, as it was last summer) and I recall lots of happy people and lots of happy natives trying to sell stuff to the happy people. The food was tasty, with good service. The atmosphere inside was very nice. I remember lots of music inside the restaurant and out. It was summer, not too cold. Things will be much different this time of year. May I suggest that you make reservations well ahead of time, especially if it's important. Have fun.
Montreal, Canada