Anything that's intrapsychic happens in your mind, like your intrapsychic conflict over whether to tell your friend the truth when he asks how you like his haircut, or to protect his feelings.
The word intrapsychic comes from the Latin intra, "on the inside," and the Greek psykhē, "mind, soul, or life." It's used in psychology to describe activity, conflicts, trauma, or any other important occurrences that happen in a person's mind or psyche. A psychologist might contrast intrapsychic events with interpersonal ones, which occur between different people. So your fight with your sister is an interpersonal conflict, but your feelings about the fight are intrapsychic.