This is a difficult question to answer because I have only been provided with a small snippet of a therapy session between your boyfriend and his psychiatrist. Taken out of context it may seem like bad advice but there may have been a miscommunication. In addition, I would need to know much more about the therapy, including: what he told his psychiatrist, how he behaved in the office, in what context her statement was made, etc., to be able to provide you with a fully informed answer.
It is possible that she told him to “hold it in,” presumably referring to his emotions around the death of a friend, because she believed that his emotions would overwhelm him. Again, I’m speculating; it is difficult for me to be certain when I have only limited information. Her advice may have made sense given his emotional state and what he relayed to her in their therapy session.
“Holding in” one’s emotions may be counterproductive but it depends what the therapist meant by this. Pent-up emotions can have negative psychological effects and even physical health effects. Being able to express one’s emotions, in a healthy and safe environment, is the ideal.
There are occasions when it is too difficult to express emotions. After a tragic event, for instance, an individual may feel numb. In other words, they feel nothing at all. The person feeling numb would have difficulty expressing their emotions because, for the time being, they feel nothing.
There are also times when an individual may not be psychologically ready to openly discuss their emotions. Sometimes, “it is just too soon.” An individual may need time to fully process how they feel before sharing their feelings.
From what I understand, your boyfriend recently began treatment. It may take some time before he is able to come to terms with his emotions about the murder of a family friend. If you and he find that treatment is not effective, then it would be in his best interest to consider choosing another treatment provider.
In closing, my answer is very generalized and based on limited information. If you would like to write back and provide more details, I may be able to give you a more specific answer. I wish you and your boyfriend the best of luck. I am sorry for his loss. Please take care.