This question could not come at a better time. I am planning on writing a hub about abuse, but I found your question first.
It's easy to say there are no reasons why a person should remain married to someone who physically abuses them. It's easy to say, "Grab the kids and run."
It's hard to describe the feelings to someone who has never had an abusive boyfriend/husband/baby daddy.
It's hard for people to realize that abuse can happen anywhere-whether it is physical, emotional, sexual, or a combination of all types. The one who suffers the most is the innocent child witnessing the abuse; their scars remain forever. Abuse can happen to men and women across all socioeconomic statuses, among all educational backgrounds.
The abuser is good at making false promises- it will NEVER happen again, they might even break down and cry, and ask for forgiveness; they'll blame others for their actions, or they'll make excuses; they'll convince their family and friends that the other person is the problem. They'll blame stress, lack of sleep, alcohol, drugs, or a metal disorder.
The truth is, there are lots of reasons why a person who has been abused stays in a relationship, but there just aren't any good reasons why!