How to lose weight when your partner likes high-fat food?

So I share a household with my BF, and he's a bit of a gourmand, and a good cook. When we make a menu and plan meals, we tend to have dishes that we both like, but are causing me to gain weight. I don't want to waste food, so I have the leftovers of calorie-dense foods for lunch, as well.

What do you guys recommend? Should I make a healthy meal for myself, and a separate meal for him on the nights I cook? Should I buy my own groceries? Should I have small meals made of veggies until dinner?