A simple fact: Nearly every day your wife does something that you could criticize.
But the important thing to think about when this happens is this: When she does something you consider "wrong" (i.e. making a mistake or choosing something differently than you would), are you choosing your preference or are you choosing her when you respond?
A few examples:
In your marriage she typically makes the bed in the morning, but periodically you notice that she doesn't get it made. In exasperation you say things in passing about how she can't get such a simple task done.
At a restaurant one weekend she gets a little careless and spills her drink all over your $8 burger that just came from the kitchen. It's ruined. You use some choice words about what she just did and stop conversing with her for an hour afterward.
In talking with her mother on the phone, she goes over your allotment of minutes for the month on your phone plan and you have to pay extra. She felt it was worth it, but you get on her case about how irresponsible you think that was.
In each situation like this, what your wife is hearing you say is that there is something else that is more important to you than her. A made bed. A burger. Seven dollars in cell phone charges. You have just made each of these more important than she is, otherwise why would you put her emotions over the fire through your critical reactions? They're clearly very important to you, and she'd better understand and respect that, right? Wrong.
What she'll be feeling (even if she isn't aware of it) is that her feelings and importance to you are on the same level as a bed, a burger, or a bill. If she were more important, why would you be making such a big deal about the other things?
Sure these are trivial things, but what about something really major? What if she loses her wedding ring? After all, that's the ultimate symbol of your marriage, and your marriage is extremely important. And in her carelessness she just lost it. This is obviously a good time to make sure she knows how much she has failed you, right? Wrong. As rich as it is with significance (and as much as it costs), it's still a simple object made of metal and mineral, but your wife is your soul mate. Which is more important—really—and how will your reaction to her mistakes communicate that to her?
It's not always easy, but be patient with your wife. Realize that next time, it will be you forgetting a chore, knocking over a drink, or losing something valuable. Forgive. Overlook. Choose her.