Where do I begin?

[DianneTurner]

My recommendation (for both your relationship and cooking!) would be to do meal-planning and shopping together. The two of you can look at the coming week and figure out what to make and when you'll have leftovers, plus what each meal might have in the way of a salad, vegetable, etc. If you have a farmer's market near you, that's a great way to buy your produce for the week, and even some prepared foods and other things. Don't prewash all your veggies, though, as this will start the decaying process. Wash as you go.

[xxdrippy]

I think we have a farmer's market I'm not sure seeing I never went but I'll look into it, thanks!

[jpmcgrew]

Here are some simple ones look at the books that customers bought as well plus you can look inside most of them.
Amazon.com: Cooking for Dummies: Bryan Miller, Marie Rama: Books

[B'sgirl]

Here is what DH and I did:

We went through all our recipe books and looked a few up online and made a list of all the meals that sounded good. Every week we would pick 7 of them and make a grocery list for those ingredients. It kept food from going bad and getting wasted because we had planned on using it all. You can plan a variety of meals to get the nutrients you need. You can find low-fat/low carb cookbooks to use since your girlfriend is on a diet. I usually put a few easy meals and at least one "experimental" meal on each week's list. Grilled cheese sandwitches, pancakes, and some wild Asian meal most people have never heard of. You can stock up on foods that make healthy side dishes like canned/frozen veggies. They are easy to heat up in a matter of minutes and keep you from stuffing yourself with the more fattening main dishes.