Going out alone does not just mean going out where there is nobody else around. I used to be out most nights - in fact there was a time when, if I was not at work etc, then Sam-antha was out, alone. Years ago. Bars - be careful -, coffee, late night shopping seems fine, but there was none then. Just get it into your pretty little head that girls do go out at night. Certainly not late, but they do go out. Like Alice b says, but do realise that you either must have company if you leave the bar late, or a car with a mobile just round the corner. It is a man's world out there late at night, no matter what it seems like.
Play along with your wife for the first time, she knows.
~Samm