Don't make a big deal that you are eating vegetarian. He might not notices.
Bake him a big gooey hotdish (I'm showing my geographical roots). It could have veggies, cream of mushroom soup, maybe some rice, cheese, etc. If it's large and greasy (not necessarily *diet* food...), he'll probably eat it.
My mom is like your meat eater. It's just assumed, to her, that every meal has to include meat. Yet she has no complaints when she comes to my house, even for holidays like Thanksgiving. I bake heavy things, like lasagna. Those recipes are so filling that she doesn't miss the meat.