*Disclaimer* this list could be SO long. Boston has great restaurants across all of the neighborhoods. But if I had to just pick a handful... here's what I would recommend!
Banyan Bar
This place just has the best atmosphere. They are a Pan-Asian Gastropub and the plates are perfect for sharing (ideal for a date!). They are located in the South End - you can check out their website here.
Lolita Fort Point
It is SUPER dark inside Lolita Fort Point - so I wouldn't recommend it for a first date, but if you've been in a relationship for a bit - check this place out! It's a trendy Mexican restaurant in Seaport. They have a great vibe/decor and the place will be packed with young adults. In the summer they have a nice patio area along the water too. If you're single and just looking for a great place to go - this is a good spot for your friend group! Visit their website here for more info.
Barcelona
Can you tell I just really love sharing plates? Barcelona is a Spanish restaurant serving up small plates and lots and lots of wine. I love ordering a little bit of everything off their menu. They have a spot in the South End, and another in Brookline if you're outside of the city! See website here.
Legal Harborside
Clam chowda. Lobster rolls. And a beautiful water view. Need I say more? Legal Harborside is the best spot for traditional New England Seafood in the city. There are a bunch of Legal Sea Foods locations around Boston - you can see a list of their restaurants on their website here.
Empire
In the Seaport, Empire is another trendy pick. They serve up Pan-Asian style food (and amazing drinks) that are also great for sharing with a date (or group of friends!). It can be a little pricey, but worth it if you take your time there - go for the experience! The food is great too, of course. See their website here.
Capo
A Southie spot has to be on this list! Lincoln Tavern, Loco, and Capo are probably three of the most popular restaurants in the area. All of them are great, but Capo would be my date-spot go to! It's an Italian restaurant with all of the pasta and pizza you could ever want. And on the weekends the basement turns into a live-band / dance club scene. Check out their website here.
Anywhere in the North End
Okay - of course there are some spots in the North End that are better than the rest. But in general? You can't.go.wrong. Seriously. I have been to more restaurants in the North End than I can count - and I've always had a great experience. The pasta is almost always home-made in restaurant at the spots in our "Little Italy" (we never call it that haha). It's basically an Italian food-lovers dream. I think last count there were just over 100 restaurants in this little charming area of the city. The restaurants are often in small spaces, so expect things to be a bit tight inside. But the ambiance is perfect for a date - and lively. You won't be disappointed!
Bartaco
Come for the tacos, stay for the margaritas. This is another Mexican spot in the Seaport district. While Bartaco might be a chain, they still deserve to be on the list! The atmosphere inside is perfect for a date - even a first date - lively, loud, and the drinks will get your conversation going. Check out their website here.
Earls
You've probably heard of Earls before. But I ALWAYS have a great time there! Located in the Prudential Center in Boston, Earls has an extensive menu with just about anything and everything you can think of on it. It's a great spot for a first date because there's something for everyone on it. Plus their monthly drink specials/deals are an added bonus. In the warmer months you can sit out on Earls' patio area - enjoying the summer sun with sangria in hand. Visit their website here.