in a society permeated by psychotherapy and psychology and psychiatry and self-help and so on and forth, many people have been to therapy, but those that haven't might have read self-help books, but those that haven't might have scrolled by a self-help post, but those that haven't have a friend that have, and so on.
examples of bad therapy-speak dialogue like: "do you want to do [x]?" "oh, sorry, i'm not sure i'm comfortable with that..." "that's, fine, would [y] work for you?" "ah, yes, probably, sorry for being difficult..." "please don't apologise this is totally valid" "<3" "<3" are conversations i have had irl. it's also, i'd say, a spontaneous mode of interaction among many people i (voluntarily) hang out with. checking in, validating, i-statements, all that.
obviously, also, we have all encountered people explaining their problems using icd/dsm diagnoses, people talking of their diagnoses, people talking of their issues using the language of psychiatry/psychotherapy, we are aware of the ubiquitousness of words like narcissism, toxic, trigger, dissociation, trauma, ptsd, my boundaries this, my feelings that, self-care. thoughtful people use this, assholes use this, friends use this, enemies use this, your boss uses this, corporations use this, advertisements use this, etc. this goes beyond gender, class, race, and background, there is no really rugged manly man left that genuinely has remained entirely untouched by this.
AS SUCH in a contemporary setting, i believe decisions must be me made not so much whether characters know (some of) these words, use (some of) these concepts, but how. would character A by the type to selfdiagnose with audhd, would character B have ever been sent to useless therapy, would character C haughtily scoff at all that but silently identify as psychopath, would character D consciously distance themselves from [psych label], would character F "misuse" [psychological term], etc. legitimately i don't think it makes sense to aim to avoid therapy-speak in a contemporary setting, or to imagine a character that would be entirely innocent of it. maybe doing so creates another fantasy, the fantasy of the "pure" the "real" the "non-artificial". where emotions and deeds are so honest, where mental illness is "real" and not "learned in a book", where characters do not preoccupy themselves with such trivial manners, where they have real problems, were encounters are raw and natural and not guided by cringe little scripts...
as for fantasy or pseudohistorical settings, it is one thing to avoid using terms like trauma, dissociation, ptsd, depression, trigger, borderline pd, because these words have no place in the setting. this is easily done. but it is another to not write what is happening according to the logic of these concepts, as learned by us. one might avoid all 'modern parlance' yet show-not-tell a flashback, show-not-tell a dissociation, show-not-tell a panic attack, show-not-tell something right out of trauma theory book. how to genuinely not conceive of this character's inner working, this character's problems and troubles following the logic of psychotherapy and psychiatry, influenced by these terms and concepts? even going "and i'm precisely NOT going to give this character this issue/this reaction" "and i'm going to make their conflict not about that" "and i'm Not going to make it about [repression/trauma/insight-as-plot-moving/etc]" is in dialogue with this. how to avoid therapyspeak in our texts and in our hearts, to truly write beyond that, in a different register altogether? this might say more about what kind of person i am and my background than it being generally true, it's hard for me to tell, but i know that personally, with my abilities and skill level, i'm not even aiming for that, i struggle to imagine what that might look like, and content myself with being as deliberate as possible in playing with the rulebooks laid out in my therapyspoken mind.