There are some communities that feel garlic or regular onions are too strong, and substitute the white of leeks. It does affect the resulting taste, but if your wife tolerates them, it’s an option.

My own suggestions for recipes would include some classic Slavic dishes where onions aren’t essential. These do exist, 😁 particularly ones that mix sweet, sour and savoury flavours. e.g., Crepes/nalasnyky filled with farmers’ cheese and butter or cream, traditionally served with sour cherry or strawberry preserves on top, are a favourite. For a savoury version, try these nalasnyky with dill in the cheese filling.

Do you know if this is some specific allergy or a general food sensitivity? I am sensitive to fructans, which are a FODMAP in all of those foods, except the green parts of an alium (garlic, scallion, onion, leek). I take an enyzme called Fodzyme which helps me digest fructan rich foods when I can’t avoid it.

Unfortunately, 40% of every dish I make is yellow onion and garlic so I don’t think I can help.

Spaghetti carbonara is always a winner. A lot of people make it with garlic but traditionally it’s just guanciale (or pancetta or bacon depending on what’s available for you), eggs, cheese, and noodles. It’s the Italian bacon egg and cheese. There are plenty of good recipes but whichever one you choose, the key to getting the emulsification right is to mix the cheese and eggs together cold and then add them to the pasta heat off while stirring quickly. Add the leftover water from boiling the pasta in small amounts until you get the consistency you want. The sauce should be creamy, not thin or chunky.

Maybe wife is vampire

So possibly try some Romanian cabbage rolls https://www.jocooks.com/recipes/sarmale/ Substitute onions with green onions since you said green onions are fine however you can also remove them if you wish as they just go into a mix of the beef

Is this part of a low fodmap diet or just a food preference thing? Either way you can get a lot of decent recipes just searching low fodmap x.

also pasta with roasted or sauteed cherry tomatoes is my go to, top with basil/parm/whatevs

You can replace sauteed onions with similarly cut and sauteed eggplants. Different flavour, similar function.

There are some Indian dishes without them. I’ve had good results making things from a book called The Art of Indian Vegetarian Cooking. No onions or garlic are used in any of the recipes and there are plenty without beans.

Oatmeal. Not exactly date night, but it’s hot and healthy.
Get large flake oats, not the instant stuff.
Boil 1 cup of water in a small pot.
Decrease heat to mid-low.
Add 1/2 cup oats. Stir only once.
Cook for 10 minutes,
let cool for 10 minutes,
eat for 10 minutes.

You’ll want to watch it closely for a minute or two after you add the oats to make sure it doesn’t boil over. If it looks like its going to boil over just remove the pot from the heat till it calms down, and decrease the heat a little maybe, every oven is diff. It still needs to simmer though.

You can season it with whatever you want after cooking it: maple syrup, milk, oat milk, brown sugar, chocolate chips, raisins or other dried fruits (if you do raisins add them to the water before the oatmeal), cinammon, apples… etc.
Maybe a small pinch of salt.