If you really REALLY want to get away from it all, and go to a small charming inn that has a day spa and a wine list that's over an inch thick. Then check out the Stonehedge Inn, it's in Tyngsboro, which is closer to New Hampshire then it is to Boston, but it is a GRAND place.
The food is excellent, the rooms are very comfortable and the staff is very friendly and there's a golf course nearby.
They have package deals specifically designed for romantic getaways. And if your special someone has a thing for fine wine, they have about 2000 bottles on their wine list, no that's not an exaggeration.
However, being so secluded, it's a bit of a hike to get there from Logan Airport, so rent a car with a GPS.
And it's relatively expensive, but the experience unforgettable.