Here we have another MN thread where some can't imagine that others may like different things to them, and that that's fine.
As a diagnosed Coeliac, DH and I have been doing this sort of thing for decades. We prefer high-quality self-catering accommodation as it's more spacious and has more facilities than a hotel room or suite, but that's our preference, others will have different tastes. We also find most restaurant food very disappointing since Covid, so I get you, OP.
Dietary issues aside, I don't think it's difficult to imagine that there might be times when a couple just want to get to their accommodation, kick their shoes off, pour the wine and start relaxing, without all the faff of going out to eat. In addition, some may prefer a quiet meal together, rather than a noisy or brightly lit restaurant.
I do this all the time, OP, and here's my tuppenceworth.
To avoid too much cooking in an unfamiliar kitchen and too much clearing up, I'd take something largely previously prepared, or easy to pop in the oven.
For a romantic night away, I think I'd take one of the following for minimum effort and a meal we'd both enjoy.
Make some beef stroganoff at home and take a pack of prepped veg from the supermarket ("stabby veg"), stab the bag and cook them in the microwave for a few minutes. Then take either a sachet of microwave rice or the potatoes dauphinoise as below. Heat the stroganoff gently in the microwave, you don't want the cream to curdle.
OR take some steak, and some butter , salt, pepper and rosemary to cook it with. ( I personally would take my own pan to cook it in, unknown pans can be tricky for this). Serve with a mixed salad, and add some Dijon mustard vinaigrette previously made at home and transported in a small container.
Then the dauphinoise. Buy a pack of the Bistro potatoes dauphinoise from Asda (the best ones I've found by a country mile), double layer in a little ovenproof dish at home and wrap well with foil. Cook them when you get there for a little longer than the packet says, and at a slightly lower temperature. Take the foil off for the last 15 minutes to allow it to brown.
Very easy indeed, and utterly scrumptious. Get a dessert from one of the supermarkets if you want one, or some cheese and crackers.
The Morrisons with the proper florists are doing some very cute little posies in a glass vase for five or six pounds for the table if you're feeling so inclined. 😄
I hope you have a lovely time. 💕