Often times when we are stuck in our own heads we build a narrative that is actually 100% false. We become convinced that it is true, so much so, that it influences our emotional well being. We are convinced that things are a certain way, believe that others feel so as well, and that internal narrative keeps getting reinforced. However, someone might come along and give you their perspective, which will almost always be completely alternative to the dialog you have going in your own head. You will dismiss this counter perspective as an anomaly and carry on with your false narrative.
This is why, it is so vitally critical to gain a diverse range of perspectives. Even if they are from people you do not like, or have different opinions than you. The more you hear from others, the more you will know the actual situation and be less prone to internal dialog that is just absolutely wrong.