Winter is a wonderland in Boston. The snow-covered cobblestone streets, crackling fires and views (now unobstructed by fall's leaves) provide the perfect backdrop for a day filled with romance. Put on your hat and gloves, and cozy up to that someone special as you make your way from whimsical fun to cozy supper and then take in one of the most spectacular views of the city you'll ever find. 
Winter evening at the Frog Pond — Photo courtesy of The Boston Common Frog Pond
Whether you're a professional skater or you've never donned a set of blades, take a spin on one of Boston's outdoor ice rinks. The crisp air inspires movement, while any trepidation is corrected with a firm grip of the hand of the one you love. Spin around the Boston Common's popular Frog Pond.
Soak up the history and scenery, including a bird's eye view of the golden dome of the State House. Or try out one of the other "view-tiful" spots around the city, such as the newly erected (and much smaller) rink under the arch of the Boston Harbor Hotel, where you'll enjoy a gander at the Rose Fitgerald Kennedy Greenway on one side and a glance at the Harbor on the other. 
View of the Greenway from the skating rink — Photo courtesy of Boston Harbor Hotel
When you've had your fill of outdoor fun, indulge in an adult drink to warm up. The Frog Pond's central location puts many spots within walking distance, including Avery Bar at the Ritz-Carlton. Home to a stunning fireplace surrounded by cushy seats for two to sink into while you sip one of their specialty cocktails, Avery Bar provides the feel of après-ski (or in this case, après-skate) in the middle of the city.
If you happen to be outside the Boston Harbor Hotel, then stroll inside and warm up with a cocktail at the Rowes Wharf Bar, where you can snack on light eats like the bar-tasting seafood plate for two, paired with a glass of their signature scotch or a selection from their creative cocktail menu. 
Avery Bar's romantic nook — Photo courtesy of Ritz Carlton Boston Common
Don't let dinner slip from your grip, because a stroll to the North End will have you stopping several times for a smooch. Enter Christopher Columbus Park's arch after dark. Marvel in the twinkling lights that encase the archway, while you walk to the cobblestone lined, gaslit splendor of North Square.
Here, you'll find one of Boston's most romantic Italian restaurants, Mamma Maria. You should request a table for two in one of the smaller rooms to give you the feel that you're dining in private. This place is well worth a reservation or a wait, as the food and the setting are top-notch.
When you've eaten your fill of Italian delights, make one last stop before retiring for the night at the Marriott's Custom House, where you'll enjoy a 360-degree view of Boston. Purchase a ticket from those at the desk (Tickets include either a soft drink or an alcoholic beverage redeemable after viewing in their bar.), and wait for your tour guide to take you to the 26th floor, where the outdoor observation deck awaits.
Even with a chill in the air, nothing can compare to seeing the skyline from every angle offered by the Custom House. The most stunning part, however, is watching the sun set from your rooftop perch and seeing the city transform as the lights begin to twinkle all around.
After viewing, make your way in for the evening to spend the rest of the evening enjoying what really matters: each other. 
Sunset view from the Marriott's Custom House observation deck — Photo courtesy of Jessica Polizzotti