Violence is really only an isolated event. There isn't much of it happening. One out of every 15 relationships are right now experiencing the sort of violence that will send the victim to the hospital. In particular, over her lifetime a woman has about an even chance of being beaten up. Domestic violence only happens to poor people or minorities.
Abuse happens in every sort of family, regardless of race, economic background or educational level.
Every relationship has arguments and stress, but most people don't hit others when they get angry. The abuser has no skills other than violence to deal with stress. Most victims are hit over little things or even beaten in their sleep. The victim actually enjoys the attention, needs the violence or is a perpetual victim. The abuser's violence is their own responsibility.