She may or may not be looking for a rich man, especially if she's going out w/her friends. She may be going on for a good time and drinking/partying only at the moment.
My advice still stands, you can't control her. Speaking to her isn't going to do any good. In fact, it may make the situation even worse because the more you try to reason w/her about her behavior the more she's going to do it. The best thing you can do is ignore her, don't say anything about her night out and leave her be. As I have pointed out before, you are not her father or her employer. Step back, give her the space she needs. I know you don't like her behavior, but you have absolutely no control over her...but you do have control over how you react to her behavior.
Try to keep the focus on you. In fact, why don't you go out Thursday evening? You could go to a movie, get a cup of coffee, take in the Christmas sights, etc. Just remember, teenagers will try your patience and that's what your wife is doing right now. Breathe, dig deeper for patience.
BTW, the more you try to control her behavior, the more justification you are providing to her as to why she needs to do what she's doing and possibly a separation/divorce. Take that justification away from her. Do a 180 and wish her a pleasant evening when she goes out. It will make her wonder what you are up to.
