Top 10 Answers... 1. It used to be (ie, quietly accepted/expected by society in past) 2. Denial is a powerful influence 3. Guys are usually not the victims 4. Provides a (false) sense of superiority/power 5. Hurt is turned into anger/aggression 6. Observed in childhood home or elsewhere 7. Bigger, stronger-they use resources that are most available &apparent 8. Lack insight 9. Unhealthy psyche 10. (they don't really).
Complicated. Domestic violence has been renamed intimate partner violence. It can be physical, sexual, psychological or threats. This is an issue of power and control. In many cultures and communities it is acceptable to treat women as property. Perpetrators can themselves be victims of physical or sexual abuse. It is a worldwide problem. There are programs to increase awareness.
Several reasons. When a sub-culture accepts that men should be more powerful than and control women, harming them to maintain control becomes acceptable. Also, if violence was witnessed as a child, a man may believe it is ok. Some men believe that it is part of "being a man." if a man was traumatized by violence as a child, he may not have skills to manage anger or his own behavior. He could be mentally ill.