I think there are many reasons, I think there is the fear of being seen as a failure. There is also the fear of being alone and having to start over again. I know women in their 50s who got back with partners who were emotionally abusive & unfaithful because they felt they are too old to meet someone new.
if the abuse is emotional, its often more difficult to acknowledge it. A black eye or broken arm announces abuse to the world. Emotional and verbal abuse gets overlooked. Women want to believe the abuser if he says "it won't happen again" and soon it becomes a pattern of life that is hard to get away from.
Women stay in abusive relationships for a variety of reasons:
~ financial concerns (they have no way to support themselves and their children if they leave)
~ fear of disappointing family/church/friends if their relationship fails
~ trauma bonding (conditioned response to repeated abuse that compels them to continue trying to earn their abuser's approval)
~ fear of retaliation
~ fear of having to share children with an abusive partner, who will then have unsupervised access to the kids half of the time
~ low self-esteem
Some studies conclude that a woman leaves or attempts to leave her abusive spouse an average of nine times before she leaves permanently.
Abuse is NEVER the fault of the person being abused. An abused person is generally living in survival mode, and taking steps to actually leave the relationship takes a superhuman effort that people cannot understand unless they themselves have done it. The last thing they need is for someone to blame them in any part for having stayed as long as they did.
As an aside, I was an abused wife for 20+ years, and I am now a counselor that supports women who have lived and are living with domestic violence.
It's not as simple as telling women to just trust in God and watch their problems magically disappear.
A lot of the women I counsel have dealt with decades of spiritual abuse from "Christian" spouses, many of whom were in ministry (like mine), and churches who demanded that she just work on becoming more submissive (I was actually told, after an incident that left me with a broken arm, that I just needed to "suffer as Jesus suffered" and praise God for the opportunity to serve a violent man).
Many times women are at the point of resenting God for allowing the abuse, and it can take a long, long time for them to trust anyone, including God.
Yes, God can do wonderfully healing things in broken lives, but He does it in His time, and it's not an immediate process. It can take a lifetime of loving support, highs and lows, "one step forward and two steps back" before a woman can truly reach the point of trusting God and healing from the deep emotional wounds caused by men who claimed to be His disciples.