We only care what others think when we fear there's truth in their thoughts. Look at it closely – we only worry that people will think we look bad in an outfit because we think we look bad in that outfit. We only care what our friends think of our relationship because we are afraid it isn't the right one. Things only upset us when deep down we think it too. This is where self-love comes in. If you're solid in your foundation of who you are and fully believe in the decisions you're making, it won't matter what other people think because you'll no longer need that external validation.