When Charles Dickens wrote Oliver Twist, he never bothered to make mention of the race or religion of any of the characters, except one. Throughout most of the novel, Fagin is referred to as “The Jew” with occasional variations on the theme. You may think his choice of words was simply standard at the time, but he was challenged on this choice. When criticized, he seemed surprised, and said, “It unfortunately was true, of the time to which the story refers, that the class of criminal almost invariably was a Jew”. He said he wasn’t biased against the Jews but was merely reflecting a simple truth about the nature of certain criminals. He even exclaimed, “I have no feeling towards the Jews but a friendly one. I always speak well of them, whether in public or private, and bear my testimony (as I ought to do) to their perfect good faith in such transactions as I have ever had with them…”
He really couldn’t see that any of this was his fault, but he eventually did change his ways. 
He did have actual Jewish friends, and as hard as it was for him to see the problem, he didn’t want to offend them. He explained, “There is nothing but good will left between me and a People for whom I have a real regard and to whom I would not willfully have given an offence.” In the last chapters of the book and in subsequent readings, he deleted the offending appellation in the way you might finally discard a favored but hopelessly stained garment.
Dickens wasn’t unique by any means. We all have biases that we feel certain are nothing but statements of fact, supported by our frequent observations. In my interactions with therapists, I often hear the phrase “usually the man” sprinkling their descriptions of couples with marriage difficulties. Something like this: “When one partner has difficult expressing emotion (usually the man) . . .).” Or, “When one partner struggles with monogamy (usually the man . . .). Or, “When one person is addicted to porn (usually the man . . .). I’ve asked a few therapists about this construction, and the response is always some variation of, “What am I supposed to say when I’ve observed this time after time in my office?”
The fact is, of course, when we believe something is true, we tend only to take note of that occurrence in our observations. Even when we are aware of our own confirmation bias, it is exceedingly difficult to diagnose our own blind spots.
Some examples:
- Dr. Gerald Stein, listing several kinds of unhealthy sexual activities, describes “selfish sex” as “a cousin to Obligatory Sex. However, in this example, it is usually the man who satisfies himself quickly, not out of duty, but simply because his needs are all that matter to him.” Note that it is usually the woman who has sex out of a sense of obligation, or so Dr. Stein believes.
- In a paper by Barry McCarthy on marital sex, he says, “A realistic expectation is forty to fifty percent of sexual experiences will be satisfying for both people, twenty to twenty-five percent are very good for one partner (usually the man) and good for the other.” He begins the paragraph by saying the data is empirical, but only cites a study on sexual dysfunction that occurs before the statistics about satisfaction, which is not cited. I’m sure his experience confirms his claims to his satisfaction.
- An article on domestic violence in Psychology Today by Neil S. Jacobson and John M. Gottman says, “In many unhappy marriages, when one partner (usually the woman) requests change, the other one (usually the man) resists change, and eventually the woman’s requests become demands, and the man’s avoidance becomes withdrawal.” Again, if asked, I am sure these therapists/researchers would insist that their statements are supported by many hours of clinical observation, and they probably are; however, it is likely that men who are victims of domestic violence are much less inclined to seek therapy because they know they will not be taken seriously as victims or because they also refuse to see themselves as victims.
I could go on and on with examples, but you can do it yourself. If you want to see how pervasive this phrase is, just Google “psychotherapy” and “usually the man” or “marriage counseling” and “usually the man.” I promise, you will have plenty of examples.
What I would like to point out is that these “empirical” claims about what men do in relationships always conform to negative stereotypes about men. Men are selfish lovers. Men are abusive partners. Men are kinky. Men are more easily satisfied sexually than women. This thinking eliminates the opportunity for men to be abused, neglected, unloved, and unfulfilled. It denies women the opportunity to be the partner who is more sexual, more liberated, or more powerful. I once sat through a panel discussion by three male therapists, and one of them admitted that his sympathy just naturally went to the women when he saw heterosexual couples.
A couple of things to consider:
First, it may be correct that in some cases men are more likely to exhibit certain behaviors or attributes than women, but assuming they do makes it extremely difficult for you to see the men who are atypical. Second, it may be that men and women are not as you perceive them to be at all. Rather than interpreting data as it appears, you may be constructing data from your own biases.
A final note:
If you wonder whether your statements may reflect a bias or stereotype, try the Dickens test: Substitute “usually the Jew” or other racial term for “usually the man,” and see how it sounds. If you aren’t comfortable with the racial term, consider revising both your words and your expectations of your clients.