well, here's a way that i could see it working.
1. shopping: since both of you eat fruits, veggies, beans, and grains, it seems that that bill can be slpit in two. if you both consume eggs and dairy products, then that bill can be split in two. if he wants to buy meat for himself, then that would be on his bill. In all fairness, you should only pay for what you eat--right?
2. cooking: it is very easy to cook vegetarian and omni meals. in my household, we cook a balanced, vegan meal and then add to it as we see fit. if i want to add eggs or dairy, i can. if he wants to add meat, he can. We always cook the meat entirely separate.
the best way to do this is to take an idea of nutrition by addition. instead of havinig him make rice-broccoli-chicken, consider making a morrocan-style meal. start with morrocan-ginger soup, then add a mixed greens salad, then add hummus and pita bread, then add tabouleh, and then if he wants it, he can add some meat to his (lamb kabobs). that should be a balanced meal for everyone (and filling). another example is mediterranian: pasta and sauce (meatballs on the side), salad.
3. keeping things separate: you'll probably want him to cook his meat in separate baking dishes or pans. i know i do. i don't want meat in my meals.