If you want to take your loved one to a nice restaurant in Seattle I strongly suggest Osteria La Spiga on Capitol Hill! It is a small neighborhood restaurant with very original Italian food.
To make sure they have a table for you - reservations are a good idea! At least a couple of days ahead of time. If you are aiming for a Friday or Saturday you might want to call a week ahead!!!
As for dishes I'd recommend anything with duck in it, utterly superb eating!!!
If Italian isn't your thing, you may want to try XO Bistro, a French restaurant on 10th Ave E (also on Capitol Hill)!
They have very nice Prix Fixe menus with 3-course dinners now and again!
Again, the Duck Confit is excellent!