The biggest cliche when talking about marriage is "Marriage is hard work." In a sense, this is of course true (otherwise it wouldn't be a cliche). But mostly it doesn't reflect reality at all, just like while saying "Singapore is an island" is true, it doesn't give you any kind of sense of what the city is actually like whatsoever.
Marriage does create work, but this is deceptive. For example, because B is a total slob my household chores are at least 50% greater than they would otherwise be: he produces more laundry than me and the baby put together by an order of magnitude. However, these losses are balanced by the gains in time you experience in other areas. If B didn't exist, then I would have to work full-time while being a single parent (leaving aside all the other things he does to contribute to the household). Somewhat more laundry is really a small price to pay. As a team, our ability to get things done is far greater than it would be if we were separated. Married people do tend to have more to do, but this is because, with their greater resources, they are able to embark on more ambitious projects (having children, extensive home renovations, intense career activities, etc.).
But the "hard work" people are usually referring to is really emotional in nature. They mean that getting along with your spouse is very difficult and something to struggle with. Honestly, getting along with anyone is very difficult (even your own children), because people are annoying, self-centered and flawed. In fact, I frequently find it difficult to get along with myself, as I continually do things which annoy me (why did I engage in that bad habit yet again, after I swore I would not? why did I get myself into this unpleasant situation, when I knew it was a bad idea from the beginning?) Marriage is not unique in this way from any other human relationship (except that, because you can select your spouse, they are probably on average less annoying to you than, for example, your relatives).
For that matter, marriage is not different from any other human endeavor: if you want it to prosper, you have to pay attention and devote resources towards it. But very few people say, "Being a sports fan is hard work" (as a fan, you have to do a lot of reading, spend hours watching programs, memorize large amounts of information, and go through constant emotional strain). This is because 1. they enjoy doing most of these tasks, even though they are time-consuming and 2. the payoff is worth the efforts, so the tasks that aren't so fun (watching your team lose), are endured for the good times. It doesn't become about "hard work" (ie, something you must suffer through) anymore, but rather is exactly what you want to do.
I think the "marriage is hard work" argument is made by people who think that (to continue the analogy) they should be sports fans, but are unwilling to spend time watching sports. It feels like hard work to listen to their spouse's problems, consider their feelings thoughtfully, or even spend time with them, and not because these things are intrinsically unpleasant (people in love passionately desire to do all of them). Enjoying these things presupposes a certain feeling toward their object, and if you don't have that feeling, then they are terribly unpleasant (just the way I feel about watching football).
So if you think marriage is hard work, it just means you and your spouse aren't getting along. Maybe your spouse is selfish, cruel, rejecting, lazy or insensitive; probably both of you are. I have found that being married is a really good way to find out more about your character flaws, which is one of the reasons I like it: it both compels me (if I don't want to argue constantly) and inspires me (since I love my husband) to be a better person. Thanks B, for putting up with some of my flaws, helping me to improve others, and making marriage exactly what I want to do, not just something to suffer through.