I believe I can help you with your concern
I can understand your concern during this double date, but actually psychologists are not as good as others think at detecting deception or a particular private issue that you want to be kept private.
Also if the psychologist is not "on" feeling like she/he is working then the psychologist will also not be analyzing you
Just like a regular person with a job, we psychologists like to turn off our work brain and just want to enjoy ourselves, so I am positive that this psychologist just wants to enjoy the double date and will not be analyzing you or your boyfriend.
Good to know. It sounds like she won't be on in that way, though is there anything can do or say to avoid triggering her on button aka work mode?
Well I understand this is a private issue and you do not feel comfortable talking about it here, but it is difficult to ascertain what to do when I am not sure what you want to avoid talking about. But try to do more listening to her and ask the other couples more questions to show you are interested in their lives. You do not have to get to personal with your lives when you talk about yourselves. Try to avoid conversations of trauma or psychological illness like depression, anxiety, etc...
Other things you may want to avoid talking about it intimacy as well, as some psychologists may take that the wrong way
Basically try to be superficial to an extent so that the other couple can get to know you, but not go into too many details about your personal life. So if this particular adventure that you do not want to talk about happened in another country, then talk more in detail about how beautiful the country was and the sights and tourist attractions you saw. You see you are talking in a lot of detail, but not about personal things
Behaviors that you want to express is be kind, nice, have a sense of humor, smile, basically be comfortable with yourselves. I am sure you and your boyfriend are a great couple and this other couple is lucky to be going on a double date with both of you
Thanks! this really helps