@Liela, there's a lot to address in your post, going to try to address them all..
I'm not really concerned with her hearing our 'bedroom fun' <_< she's a grown *** woman and she knows what men and women do.. Now if there was a 'louder than average' noise going on, I might avoid eye contact for a couple of hours.. but it's not uncommon for me and my wife to discuss 'bedroom fun' (nothing in detail, just references and the like) stuff right in front of her.. This usually results in the typical 'that's nasty' response from the MIL, but what can I say.. She's a grown woman, and she's not a total prude..
Next thing, it's my grandpa.. If I was too cook anything for my dad, it would be a puree of antifreeze and cyanide. His condition is a recent development and he's lost a lot of weight and has been growing weaker, he's been unable to really eat for weeks, and then a week or so ago we finally found out what was going on, he went and bought a bunch of baby food, and wife thought why just buy that when we can get a blender and do the the same, so now that's what we're doing.. I'm the one that fattened up her mom and put some meat on her bones, so I guess now I have to do the same for him.. He's been malnourished and I'm guessing (I'm not privy to all these details, my wife talks to them more than I do) now I get to do the same for him, except all the meals he'll be eating will be grinded into baby food first.. I'm a southern cook and if there's one thing southern cooking can do, it's fatten you up.
Also, me, wife, son, MIL and my grandparents don't all eat the same dinners.. I cook for me my wife, MIL and son, and my grandparents and son eat entirely separately, we have our fridge, they have theirs, we have our groceries, they have theirs.. And yes, son is in there twice, on any given day he decides what he'd rather eat <_<.. My grandparent's don't really cook, they just buy.. KFC, Little Ceasar's and TV dinners is what they usually eat. I cook, I take pride in cooking everything from the most basic ingredients and creating a dinner not packed full of additives and preservatives.
Today was my wife's off day, and she works a later shift tomorrow, it's one of the few days where she can get a good night's rest.. I don't really blame her for going to sleep or anything, nor do I question it. Still, it's part of the circumstances of tonight.
Me and my wife have different tastes.. I'm perfectly happy with meat, and meat as a side dish, and meat as a second side dish, I really don't care for pasta/rice/beans or vegetables.. I do really like some, but I'd be perfectly happy to just eat meat 24/7.. My wife on the other hand is as close to vegetarian as you can come while still eating meat.. So I try to balance them out.. That said, I cook what I cook, and I very much agree with Art, if you don't like what I made, you're free to find something else. More for me. Unless it's a special request from the wife, I cook what I'd like to eat.
Finally the snacks thing.. She has plenty she can eat other than what I cooked, it's not as if she's going to go hungry because no one told her.. It's not that she's going without food that bothers me, it's the the fact that I'm so stubborn and socially awkward that I didn't want to have to tell her 'hey come get food' and she heard us that makes me feel bad.