I don't know if this is true, but I think it's realistic enough to make a plausible example.
Many people would conclude sexism, gender roles, something like that. That's the fallacy of mixing up correlation and causation.
People ought to think harder about possible alternative explanations. Is there any other reason most TV show therapists might be female?
Here's one: it could be that most main character are male, and most therapists are the opposite gender of the main character.
In that case, the choice of the main character might be sexist (I won't get into debating that here), but the choice of the therapist would not be sexist in the normal way. The therapists would be chosen because, in some ways and some settings, people find male-female conversations more interesting than male-male or female-female. There may or may not be something wrong with people's preferences about that, but it's not an example of the standard, typical sexism and gender role stuff which someone might have initially assumed.
If most therapists really are female (maybe, I don't know), is this alternative explanation true? Again, I don't know. What I do know is most therapists being female would not rule out this non-sexism explanation!
This is a practical example of how correlation doesn't imply the first causation you think of, and you need to look for alternatives.