It is not really about driving, it is about control. It bodes ill that this man is so insecure that allowing your sister to learn to drive is any kind of a threat. Being dependant upon other for travel of any distance is a form of entrapment. Perhaps there is some abuse going on here, since normal healthy relationships do not create dependencies of this nature.

Perhaps it is not a joke that she would drive away and leave him, perhaps it is what she would do. This man is not only insecure, but I suspect a danger to your sister's health and well being. What would happen if she chose to ignore his dictate that she not learn to drive and learned on her own? Would he become violent? Her feeling trapped is another indication that the relationship is not a healthy one. You do not mention offspring, but they also would be in danger if this man is as I suspect, in emotional need of total control of your sister.

You also do not mention any religious dictates that would preclude divorce or separation, or any cultural taboos such as some muslims have. In many muslim countries, women are no more than property, and if this man comes from one of those, then there is some basis other than insanity for this apparent abnormal control issue.

I know if I had a sister, and she was in this kind of negative relationship, I would be urging her to leave the man, and seek protection from him. (such as a woman's shelter.) The person you are describing could easily batter his spouse, or even kill her. This of course is a worst case scenario, but if anyone tried to control me to that extent, and I was unable or unwilling to stand up to him, I would be on the first bus, plane or train as far away from them as I could get.

Abusive behavior also includes psychological abuse, such as threats of violence, verbal put-downs, sexual assaults (no means no in my book)

Some women who get out of abusive relationships are just dying to get into another relationship as soon as possible. Many feel they have been psychologically alone for a very long time and this is actually the reality of the situation. Since they have not taken the time and effort to do some soul searching, they are at risk for repeating their mistakes and put themselves into the danger of falling into the same trap of an abusive relationship.

A poll of 7000 women conducted by WomanSavers.com found that 55% of women have been sexually abused at some point in their lives. Frequently this abuse occurs during childhood, and when this happens, they tend to marry abusive men thus repeating their abuse patterns.

There are many groups who can help abused or battered women out there. If you find you sister is being abused either physically or emotionally, perhaps you can get her in touch with one or more of them. Behavior patterns take time to change, so finding the councilling that will help her is far better than turing a blind eye to the problems in her relationship citing that it is really "none of your business." Communication is the first step.