I have this same problem with my girlfriend. It is HER house, and she does almost no cleaning. The sink is always full of dishes, she never vacuums, never picks anything up, dishes all over the house, piles of junk mail that aren't getting thrown out, piles of laundry in the bedroom, piles of laundry in the basement (that's where the washer/dryer is), it drives me nuts. So, I do most of the cleaning.
Why?
I am a neat freak. I like things orderly and tidy. I clean most of the house once a week, except for her junk mail and her laundry.
We do not live together....yet.
Right now, parts of the house look like a disaster area because we are in the process of remodeling and painting, so it's worse than normal. Wait, I should say I am in the process of remodeling and painting, because of the five rooms I have done, I've done 85% of the work. She offers to help but is in the way more than she helps.