Romantic fine dining--definitely Back Bay Grill. Hugo's is also fine dining for now, but it's changing its concept this spring to be more casual, offering a la carte choices not just prix fixe. Another possibility is Eve's at the Portland Harbor Hotel.
While both Fore Street and Cinque Terre are tops, I don't consider either romantic, ditto for some of the other places mentioned, but other people's definitions vary. You can't go wrong with Back Bay.
If you want a little more bang for your buck, Vignola can be a nice, cozy place to share a meal on a slow night.
Also Caiola is smaller than some of these spots, great if they live on west end - they can walk.
Cafe at Pat's would also be a great choice for something a little off the beaten path.
re: Get In My Belly
I think Hugo's provides a fantastic dining experience, perhaps fitting the bill as a gift. And I think they deserve a degree of pride in regards to what they provide to the demanding diners in Portland...they have also recently promised to shake it up with their Spring menu ... proving they do not rest on their laurels and they respect the competition.
I, unfortunately, have had less than stellar experience at Cinque Terre.
I am trying to get into Bresca as the press on it is so good...but it was fully booked for 5:00 on a Wednesday (only 20 seats.)
Other suggestions...Ribollita, 555...and the new greek place Emilitsa also has a buzz.
Also, Portland has a calendar full of tasting/wine events which may provide a really special dinner at any number of restaurants. Try the blogs or individual restaurant sites on www.portlandfoodmap.com for schedules.
Well, knowing how many Portland food afficionados regularly view this site, you'll likely to get lots of answers. For me, for sheer excellence of food, traditional "white tablecloth" romantic atmosphere, and excellent service, #1 would be Back Bay Grill. I could imagine Hugo's getting some notice, although it's quite a bit more pricey, and at times, a little tedious in its pride over its menu. Cinque Terra would definitely be my #2.