Hmmm... this is something I've been mulling over myself lately.
When I met DH, he was self-sufficient and perfectly capable of looking after himself.
I love cooking, so our agreement that whoever did the cooking didn't have to wash up basically meant I cooked and he washed up. We split everything else down the middle.
We had the kitchen re-done and bought a dishwasher - so now he will load it but very rarely does he unload it, so that's something else I've got to do.
Along comes DD and suddenly I get this 'I've worked hard all week so I need (I don't think he'd dare say he deserved) my rest at the evenings/weekends. I had PND after DD and I hate to say it but I think at the time (and still to a large extent) believed him and thought it was all my fault that the house was a bit of a tip and I ought to be on top of it all, after all, I was at home all day. Although I can now see that for the complete BS it was, considering that DD had incredibly bad reflux and I spent a good 4 hours of that day walking her around held upright in a vain attempt to prevent her screaming, I still feel inadequate that the house gets messy, like I'm failing.
Logically I know that's crap, but he has this absolute refusal to accept that any of the mess is his. Or to help tidy it up, because he didn't do it (we're talking newspapers piling up, laundry put out to dry and not put away, DD's toys/drawings/play stuff). He gets angry if I challenge him on this and, largely because I feel guilty that I'm not keeping the house tidier (because I'm a messy article), I don't push it. Perhaps I should. I work 3 days a week in a very pressurised environment and am exhausted by it. He doesn't seem to get this at all. I made a joky comment on another thread, that he read memoo's list of jobs and said 'you see, that's what you need, a routine' when I'd pointed it out to him to say how appalling that this woman had to do everything by herself... it's not feeling so funny right now.
I'm making him sound like an arse and he's not (this aside), it's the only thing we ever argue about, I know that I back down too easily. It seems like since DD was born I've lost every bit of assertiveness I ever had (and I used to be quite bolshy).... but I don't want to leave him, and I don't think any of the women the OP is puzzled by do either, they just desperately want to feel not taken for granted by the man they love.