Boston is a restaurant haven. The North End specializes in Italian (you can eat dinner and then hit one of the dessert places for cannoli), there are waterfront places with outdoor seating for great steak and seafood, small cafes on Newbury Street, expensive but great views from Top of the Hub on the roof of the Prudential Building, and there are ethnic places of every shape and size. You can look up the Phantom Gourmet (which does a lot of local food TV shows) for hidden gems that suit your SO's palate. Without knowing his tastes, it's hard to give a definite recommendation.
I'd stay in Boston rather than waste time heading out to surrounding towns - you're only here for a weekend and there's plenty to do.
Quincy Market is a colonial marketplace that's now a lot of food kiosks (not all fast food by any means) plus restaurants and shops. If it's oppressively hot or raining, you could do the Museum of Science or the Aquarium (which just re-opened its giant ocean tank). There are a number of Boston Harbor cruises, from dinner cruises to 90 minute narrated harbor cruises which take you past the Boston Harbor islands and the USS Constitution (Old Ironsides). And there are Duck Tours in amphibious boats that do the city streets as well as a segment right into the Charles River. They give you an overview of history which might suggest some places you want to revisit.
Boston is a haven of history as you know. There's something called the Freedom Trail which is a self-guided walking tour. There is a red stripe literally painted on the sidewalks and you can pick it up and leave it anywhere you want - Paul Revere's House, old churches and burying grounds, lots of things you can look at if you're into that.
Boston is a small city and it's easiest to get around without a car. Use the subway system (color-coded and easy to follow) or cabs.
Your hotel concierge will have plenty of recommendations for restaurants and also sometimes they have an "in" for reservations. You can find a lot of info on the stuff I've listed on line too. Let me know if you want more specifics - happy to provide. I've lived in Boston and also outside of Boston for decades. My son just got an apartment in the city and he's having a fabulous time exploring.