It's likely that there has been a couple in your life that you've had certain...opinions about, let's say. Maybe you really don't like one half, or think some of their habits are a little odd, but they're in love and happy so why would you bother them, right?
Some people don't get to that last part, and instead openly insult any couple they come across that they don't like. When one woman was the victim of many such comments, she spoke out against them.