Seeing through our eyes and thinking from our minds is how we interpret situations. We can't do that from another person's point of view. This makes it difficult to read the room, especially when you lack social cues.
When engaging with people, everything happening in the moment is your side of the story. In hindsight, you'll get the chance to see whether your reactions were appropriate or not. The more we attempt to see things from the other person's perspective, the easier it becomes to read the room.
Naturally, we'll never get to know the full context of what another person thinks. It's still good to acknowledge that there's a whole other side.