It's a strain. My SO is a vegetarian but will eat fish, I was veg for a long time and don't like fish. I love meat.... and chicken and pork. My husband hates beef, pork and chicken.I don't think my wife is being selfish at all. (Though I don't think the above post was in jest!) It's a major change in lifestyle for the whole family and requires careful transition not to upset the delicate balance that is our family equilibrium....OWWW! That hurt my brain! I am getting great ideas from this post and want to thank everyone. This has led to some very positive discussions with my wife.
From the cook's perspective, it is a pain in the ass to make two meals, even having the same sides and a different protein. He misses casseroles (like a big thing of eggplant parm) but I get annoyed because they are a lot of work, I won't eat them and he can't finish them so they go to waste. He misses home made bread- another PITA to make. You are in the opposite spot... so whatever your can do to take work off her plate is great. Fire up the grill for your own chicken and be happy when she makes green beans, offer to clean up etc. etc.
And don't be a jerk about her diet.... and she won't be a jerk about yours. My SO and I concluded that we have different diets needed to be healthy and leave it at that.
The other helpful thing would be a list for your wife of meals/foods you like and can eat. My SO's tastes change a lot so I am now requesting a weekly list of requests for meals. The worst thing about my SO is he is a *(^*%&&% picky eater and stops liking things like a 2 year old. His mom used to make 3-4 options each meal.