maybe because one of the two doesn't know how to cook? ..i'd get really tired, and quite literally, sick of frozen tv dinners on his night to "cook".

I am another one that is so tired of cooking, but I don't see any relief in sight. DH used to cook very rarely, but doesn't try to do anything anymore. I am a good cook, and I do most everything from scratch, to try to avoid harmful food additives, too much salt and sugar, etc. But I rarely enjoy it. We don't eat out very often at all, for the same reasons.
I don't think it would be fair for me to declare I'm not cooking anymore. He might decide he was not going to mow or take care of the vehicles, etc. We have divided up the chores similar to our parents' generation. Sad, but it works.

I love cooking and trying new recipes. Fortunately, my elderly mother doesn't mind trying new recipes. I only have to cook one good meal a day. We both like leftovers, so we usually get at least two meals out of every cooking. She does the dishes, but I do most of the actual cleanup. It's not a bad deal for either of us.