Speaking from personal experience, it takes a long time to get over something like this. The police, reputedly, are not as bad as they used to be. If she doesn't report what he did, what is to stop him doing the same thing to somebody else? Or to her - again? I'm sorry to have to say that, but sometimes people do that - like child abuse, if the victim doesn't do anything about it, the rapist takes it as a sign that what they did was okay, even welcome.
I feel that reporting the crime will make her feel more in control of events and that is what she needs right now. What else she needs is to give up drinking more than a couple of drinks when she goes out. I know it's not fair - but a sober woman is more in control of a situation than a drunk man.
Also, self-defence classes could help. Feeling that you can deal with being physically assaulted is helpful - also doing something like that with your body helps you get back into it after you feel it's, kind of, been taken away from you.
All the best to you.