Well, if its a long distance relationship... is there really anything she can doa bout him going to the strip bars? If she is that uncomfortable with it, the thing for her to do about it is walk away.
Dating is dating. If you see something you aren't liking it's as easy as walking away from the situation.
If she sticks around it will probably only get worse.
Welcome to the forum. Well, does this make her mad? Some men love those places, that's for sure. I personally wouldn't be interested in a man that did. Not all men do such as the man I married.
So, your friend needs to understand and remember why we date. We date in order to decide if there is enough there to move the relationship to the next stage. Not everyone we date are we supposed to stay with forever. So, perhaps this guy just isn't a keeper.
One should never ignore something they view as a red flag.
good luck to your friend.