If you're "in love" every vacation destination is romantic! :)
However what really determines the type of vacation you have is not only who you go with but also the itinerary you have planned.
Going with a group can be fun if you're simply looking to go on daily tours of Eiffel Tower, Louvre Museum, The cathedral of Notre-Dame, Moulin Rouge, open air bus tours, The Arc de Triomphe, a cruise on the Seine River, and shopping along Champs-Elysées as well a trip to The palace of Versailles are all things you could enjoy in a group. I was with my wife but I'd have fun either way.
Oftentimes what makes a vacation "romantic" are how you feel about the person you're with, the dinners in nice restaurants, photos taken together, and (creating memories) as a "couple". The actual attractions themselves are no less awe inspiring in a group.
Bottom line is it comes down to what type of vacation the traveler wants to have. However if you have no one special in your life and have an opportunity to go anywhere I would not wait for "some day".