It either means she wants or needs more than is reasonable, or else it means you don't really understand what, exactly, she'd really find helpful (in which case, you should ask). It could also, however, mean that she is overwhelmed with responsibilities and work, that you don't realize how much she has to do, and that what looks like "enough" to you just isn't.
I think you should try to have a real conversation about whatever there is that each of you needs to do. Listen to what she has to say, and ask her to listen to what you have to say. Try to figure out priorities, what has to be done each day and what can wait to the weekend, etc. Try to think of ways of preventing some work from having to be done at all (for example, don't let things pile up and turn into a big, overwhelming, job). Try to think of ways to make some tasks easier to do. Think together about whether there are ways to structure the "task time" better.
On the one hand, people who work full-time really do get tired. On the other, people who work and live alone still have to keep their own homes clean. When children are involved they're both parents' responsibility, so the idea of getting enough rest is, unfortunate, often not a reality. It should be possible for two people to keep a place clean and do what needs to be done without any real problems (unless there are children involved, in which case, concentrate on what needs to be done for them, get them to bed at a decent hour, and let some house tasks sit until the weekend).