I am not clear if you are in a "romantic partnership". you just say my partner. Paris is the most romantic city and it is great in the winter. Cold, great light in the afternoon, fireplaces, great bars and music apart from all the usual stuff that Paris is known for.
I agree with saving the "countryside" for another time. Maybe a one day train trip to Annecy would be nice. Great lakeviews with background mountains and a very nice, albeit, long train ride.
If Paris does not move you, I agree with Barcelona combined with Madrid or Prague with a sidetrip to Vienna or Berlin.
I would definitely stick with a big city.
Let us know what you decide.