But they are, at the root, just words. When they are written by a troll from whom you are divided by keyboards, screens and servers they can have a powerful effect but they can also be avoided.
Then there are words you cannot escape, because they come from the mouth of a person you share your life with. The person who knows your flaws, your secrets, and the inside of your heart.
When a partner uses the same words as a faceless no-mark on the internet, they have a more devastating impact for the simple reason that you see the anger in their eyes, the spittle flying from their mouth, and know these things are coming from a person you love and trust more than anyone else.