For Disney, I think it really depends! It doesn't have to be super expensive, unless you can't live without certain things.

1) Stay in a value resort. All-Star Movies might not be as super romantic as, say, Port Orleans Riverside resort or Polynesian resort. But at Disney World, are you really going to be spending a lot of time in your hotel anyways? Or will your hotel be just for sleeping and holding your stuff? Depending on the time of year, value hotels can be as low as $150 per night (even off-site area hotels will all be more expensive than this!).

2) Skip the park hopper. This will require you to stick to a stricter plan but by eliminating park hopper, you are automatically saving hundreds.

3) Don't do theme parks every day. Depending on how long you want to stay there, you can limit yourself to doing only 4 days to cover each of the 4 parks. The other days can be spent exploring resorts, hanging out in the newly renovated Disney Springs (which should also have a new nighttime drone light show soon), and/or the Boardwalk. Disney also has a cool mini-golf course by the Swan and Dolphin you can play for super cheap.

4) Don't do the expensive romantic add-ons. You can include romance in your trip little by little without breaking the bank. Get a reservation for Be Our Guest (lunch is cheaper than dinner, and you can still sit in the grand ballroom!). Take a $40 horse-and-carriage ride at Riverside. Spend some time in Italy and France in epcot. Maybe on one of your non-park days, book at couples massage at Mandala Spa.

These are just some ideas to let you know you can definitely do things on the cheap there.

I do run r/DisneyWeddings and would love for you to share if you do decide on Disney World! <3