ICouldHave - do try sitting at the table together, some days at least. It might make a massive difference in terms of conversations. I also find that I have to spend at least 15mins, sometimes more like 1hr, with DH not talking very much and seeming rather grumpy, before he'll suddenly come out with something that's worried him during work that day.
If you cook food that tastes as good heated up (casseroles, stews and so on - usually the advantage is you can also batch cook and freeze), and serve it on a decent plate at a table which doesn't have the remains of everyone else's dinner on it, while having a tea / yoghurt in a bowl / piece of fruit on a plate etc yourself, it feels a lot less depressing. Also it means that his dinner is ready at whatever time he comes in, but you don't have to worry about waiting. Sometimes I eat 3/4 of a dinner at 7.30pm, and then put a small amount on a plate and eat that at 9.30pm with DH.
Days when DH comes in at 10pm and starts hunting around the fridge for something to eat and then eats it in the kitchen on his own are just miserable, in our house at least.
Hope this is some vague help, if not really addressing the fundamental problems.