There's just tons of stuff you can make that'd satisfy him that you're probably just not thinking of because you cook with meat normally.
I've made a bunch of this stuff for friends who eat meat and they don't even notice they're eating veg., really.
Try a hearty vegetarian lasagna - I like a white one, personally, though you can do red sauce. Whole wheat pasta is more filling, and a good bechamel too. I do white with layers of pasta, ricotta (spiced with egg, like normal lasagna), and whatever veg are handy, usually some combination of carrot, broccoli, spinach, cauliflower, grilled portabellos, some mozzarella. Top with more bechamel and parmesan, it's giant, hearty, serve with garlic bread, it's a filling meal.
Mexican food - I make quesadillas all the time because it's a like 15-minute, no mess meal to put together. Use refried beans, grilled or sauteed mushrooms, spinach, asparagus, anything you like, bunch of cheese, some jalapenos, make a few in different varieties, pop em in the oven or on a grill, slice into wedges, make a big platter, serve with greek yogurt (has a ton of protein and is therefore very filling for very few calories and with healthy probiotics) and salsa for dipping.
I also do enchiladas - take tortillas and put a line of refried beans or stewed beans, or grilled mushrooms (grilled portabellos, sliced, are very "meaty" they have a "meaty" texture, if you grill them they get a nice charred smoky flavour, they're delicious and super versatile) or whatever, add cheese, add some spiced rice if you like and a little salsa, roll up, put in a baking dish and pour salsa or enchilada sauce all over, sprinkle cheese on, bake in the oven til all hot 'n' bubbly.
Stir frys - bunch of veg, savoury sauce, served over brown rice.
Roasted veg - even my friend's dedicated meat-loving, veg-hating husband LOVES this one - take a bunch of root veg (carrots, parsnip, sweet and regular potatoes [the wee baby regular are good for this too], brussel sprouts (even people who hate them, love them this way), a head of cauliflower cut into smallish florets, a turnip, small onions or a regular onion cut into big wedges, etc. Whatever strikes your fancy.
Cut it all into pieces about the same size, like an inch-and-a-half ish to two inch sized pieces. Toss in a bowl with a bit of olive oil (if you'd like, add some splashes of balsamic vinegar), then dump onto a foil-lined baking tray or two.
You want there to be a bit of room between each piece of whatever. Not like inches of room like cookies, just room so the stuff doesn't steam together. Salt and pepper the trays well, stick into a 400 degree oven for 25 or 30 minutes. While it's cooking, make brown rice, or couscous or quinoa, butter the grain, sprinkle a bit of lemon on, dump the veggies over, it's fantastic.
There are also tons of pastas, don't forget you can have big sandwiches for dinner - big roast veg sandwich with cheese, let it get a bit melty and crisp in the oven - or sandwich and soup. Make homemade pizzas, with tons of toppings, you can bake them on the grill.
Someone mentioned soups and stews, which can be really hearty. You can do stuffed baked potatoes, lots of veg, lots of cheese melted on, stick under the broiler for a sec... there's really a ton of stuff.