My first thought was that he's looking for things to pick at. But then, I get sick of eating the same thing if I have to too often. Sometimes I think "if I have to eat so-and-so again I think I will actually cry" but then, I'm normally the one cooking, so I can usually find a way around it myself. I also pick the mushrooms out if they are big enough to see. But, that is the only thing I would pick out of any meal.
In terms of solutions, yes, he does need to be more appreciative of your efforts, and yes, he does need to learn how to cook. Did he enjoy his own soup, btw? Maybe he could cook one night a week, and make some suggestions for a meal plan for the rest of the week? He needs to contribute in some way, rather than just eating what he likes and binning the rest. It must result in so much waste, that would piss me right off.
Alternatives to rice and pasta could be mashed potato, chips, quinoa (not sure if he would eat it but it's worth a go), cous cous, bulgar wheat, noodles. Those Ainsley Harriott packets of cous cous are quite nice, the yellow one especially. Cous cous is pretty easy to flavour yourself though if you buy it plain, but the packets are convenient if you are short of time or cba.