Hi, Amanda. I have a similar problem with my husband. He's always been able to eat exactly what he wants and still stays thin. He just doesn't "get" why people are fat ("why don't they just eat less"). Anyway, I can definitely sympathize with you when you say that you sometimes just give up and eat what he's eating. That's so easy to do, especially when you get home from work and you're just too tired to bother. I'd love it if he could just eat what I eat, but at the same time, I don't think it's fair for me to tell my husband that he cannot have certain things in the house simply because I can't eat them (why should he suffer).
I handle this situation by making sure I stock our refridgerator and pantry with "my" foods too; this is a little more expensive to do, but it's necessary. Also, I make sure he knows that I plan to stick to my diet. In the past, he'd have dinner ready when I came home, usually something like chicken parmesan (fried chicken cutlets with full fat parm cheese) and pasta. I told him in no uncertain terms that I would not eat that kind of meal. Now he cooks that kind of meal for himself and I'll broil a chicken breast and have some veggies. Granted, temptation stares me in the face, but I think that the more you say no to that kind of food, the less it tempts you (you get your palate used to certain foods). Just be sure that you have your own treats on hand so you don't feel deprived (I bake a whole pan of No Pudge brownies and freeze them individually; when I want one, I just take it out of the freezer, nuke it, and I have dessert).
Good luck. I know how hard that type of situation can be.