Regardless of how good or bad your relationship with the boss is, the boss can never know exactly how you feel. For times when he or she has inadvertently frustrated or angered you, Marcia Reynolds shares some tips at Psychology Today. She has a straightforward technique to try for conveying how you feel.
First, after a difficult conversation, decide what negative emotion you are feeling. Second, decide what tangible or intangible thing you wanted out of the conversation that the boss did not give you. Third, decide how you would prefer your boss to act moving forward. In the actual meeting you set up with the boss regarding the topic, briefly restate what happened from your perspective, state how it made you feel, articulate what you need moving forward, and then let the boss respond. Reynolds says that, even in situations where the boss responds poorly, he or she is likely to make adjustments that better accommodate you moving forward.
For examples, you can view the full article here: https://www.psychologytoday.com/blog/wander-woman/201502/how-tell-your-boss-how-you-feel