Alcohol does not cause violence. People who use violence against those they are in relationship with, choose to do so. Alcohol can create situations where people are less in control of themselves, and can reduce inhibitions to doing things they would not normally do, but this does not excuse the use of violence, and cannot provoke the use of violence.
Studies have shown that even though alcohol is involved in some cases, these same cases also report abuse and violence during sober periods.
Some people say that the violence only happens when alcohol is involved, or that it is much worse when people are drinking. This may be the case, and is useful information for safety planning, but still does not excuse the use of violence. Violence is a behaviour, and behaviour is always a choice.