I think its weird (read: rude) when one person in a household only cooks dinner for him/herself and sits down to enjoy it without asking the other person if they are hungry. Even if you are sure the other person may say, "no, I'm not hungry, but thank you". I've seen it happen in other households but I don't want it to happen in mine. Especially when I normally cook the meals in the home but was unable to at the time because I was busy caring for the baby. I think I just expect reciprocity.
There's nothing wrong with doing the "courtesy dance" in the off-chance that your significant other may accept your offer of a meal. Hey, a dinner of franks and beans can look awfully tasty even to the pickiest eater if one is exhausted enough. And yesterday, I was exhausted enough to accept that meal had I been asked.