The use of violence to deal with feelings is a choice. The choice depends on who he is dealing with. For example an abuser won't lash out and hit his boss because that is inappropriate. This question is often the first question people ask, but it is misdirected. This question is also misinformed.
Many women leave every day.
Leaving doesn't always mean protection from future violence. Leaving is a multi-staged process. On average a woman leaves and returns six times before she leaves permanently. There may be a lack of support from the criminal justice systems. A woman may be dependant on her husband for economic support.