Several years ago, I was at a local park just as a neighborhood football game was ending. You need to practice your catching. I watched the boy slink along beside his father, his enthusiasm gone. He meant well, but his response diminished the boy's accomplishment. And, in the long run, the boy would find it more difficult to ask his father for help.
Many people have pre-conceived notions about their spouses or children that hamper communication.
Don't assume that you know another person's thoughts or feelings. Doug and Mary had been playing The Ungame for about 30 minutes. Mary drew a card that asked if she ever felt lonely. Her husband blushed. Doug's mouth fell open.