She's already married to him and they haven't reached an agreement yet about having kids?

Sorry, but there's some fault on both sides about this. Whether to have kids or not is something a couple should discuss BEFORE they get married.

If they did discuss it, and he agreed in principle that he wanted to have kids, but he didn't say when, then she needs to say, "Sorry I didn't bring this up earlier, but the time is NOW."

She should resolve to solve the one BIG problem before tackling the little ones. Too many people try to solve the little ones first, but that's back-asswards. Anger from the big problem will spill over into the little ones, and you end up blowing up over trivia.

Maybe after she gets pregnant, she'll find that she doesn't give a damn about the wallpaper either.