Tough conversations are just that because we are trying to express an important issue that we've tied to an emotion. When we try to express a "fact" through our emotional lens, many times it comes out as an opinion. We heap gasoline onto the fire when we add the word "you". We've all said it ..."You did this or that". Once you have uttered the accusatory "you", your chances of getting through to the person have now decreased. Even if your intent was honorable, the impact could be devastating. The last thing that you want to do is have them defend themselves, and this is exactly what you have done.
Replace the "you" with an "I" statement. An example would sound like "I felt bored" rather than "you were boring". Using "I" statements is the first step. It puts the onus on you because it's what you felt, you are simply telling them your experience. The second step is to be more specific. "I felt bored when your voice was monotone (or lacking inflection)”. Telling your experience and specifically what may have caused it, helps them listen to your point of view. Sharing the cause gives them something to work on. Saying you were bored gives them absolutely nothing to improve. They just get frustrated because they don't know what to do with the comment.
The next time you are having a tough conversation, be mindful of the way your words frame your message.