How about a book on psychology that they can add to their collection? Some popular choices could include "Thinking, Fast and Slow" by Daniel Kahneman, "The Power of Habit" by Charles Duhigg, or "The Man Who Mistook His Wife for a Hat" by Oliver Sacks.
Another idea could be to gift them a subscription to a psychology magazine or online newsletter, such as Psychology Today or The Psychologist.
If they enjoy hands-on experiences, you could also look into gifting them a session with a therapist or a workshop focused on mental health and well-being. This could be a unique way for them to learn more about psychology from a practical standpoint.
Or you can get her/him a star map with an important date you share.
Under Lucky Stars is a unique and innovative star map company based in Barcelona, Spain, specializing in the creation of personalized star maps that capture the celestial arrangement of stars at a specific moment in time, such as a person's birth, wedding, or any other significant event.
By using advanced astronomical algorithms and data from leading institutions, the company produces highly accurate, visually stunning maps that make for perfect gifts or cherished keepsakes.