The fundamental flaw in the premise is you cannot know what you’re doing “wrong” to not get it. If you’re not literally the other person, you can’t observe every string of thought that goes through their head. If they know how much you rely on their approval, their brain will automatically consolidate power over you, issuing approval and disapproval alternately based on how it will force you to maneuver in the course of getting their own needs met. The only thing a person can successfully control in a healthy way is themselves. So you’ll end up getting disapproval when they are tired or cranky or whatever without them necessarily even realizing what they are doing. No human other than yourself can be the never-ending source of approval you desire.

If this is happening, it’s likely you’re locked in a toxic codependent relationship in which the other person is getting a LOT more out of the relationship than you.

If this is about a boss (and this is where it gets exciting) you’re being managed in an oligarchy. You’re not allowed to be happy and feel constant approval because they are controlling you.