I can't eat meat, dairy, eggs, or gluten (wheat, barley, rye, oats) and I have to avoid or limit some other foods (green peppers, soy, pineapple, walnuts, etc. ). I have Celiac and multiple allergies and food intolerances.
I certainly have staples and favorite dishes (beans, rice, corn, gluten free pastas with sauces, flat-bread, lots of fruit and veggies.) , but even with a limited diet (and budget) I don't have trouble with food fatigue. I have been exploring the cuisines of cultures that use a lot of the same ingredients I can eat. Indian food, Mediterranean, dishes from the various Latin American countries, Middle Eastern, Asian, etc. Many dishes I have found use or can be easily adapted to ingredients that are off limits to me (which may work for you), and I have also been able to find many that I can adapt to my needs.
I live in an area where I can find markets that carry the spices and ingredients that make these dishes unique. If this is not the case for you, ordering online may be a possibility to consider. Health food stores also carry some ingredients you may not find at a supermarket.
I'm not picky (can't afford to be), but even I have foods I just don't like. For instance I have hated eggplant my whole life. But roasted and pureed with tahini, it is one of my favorite foods. I'm going to try some Japanese eggplant soon (as long as I can keep the critters from stealing/ruining the ones I'm growing), as it has a milder flavor, so hopefully I can expand my diet even more.
One of the benefits of my exploration has been finding stores that carry the staples I use in bulk at low prices, without having to pay for a membership. This has made stocking my cupboards(and closet, etc.) much easier for me.
With my favorite dishes, I try to regularly change things a little bit. When I first went gluten free, (I was already vegan) I didn't know very much about what foods were gluten free. I ate a lot of spaghetti sauce, rotating between 3 or 4 different shapes of rice pasta. I still vary my pasta this way, and I change up the sauce too, sometime I add mushrooms, or capers, or olives, etc., or I make a simple marinara. (I also now know how to make many other sauces too. Heh.)
(Sorry this is so long, but hopefully it helps. )