Hi OP thanks for your response.
I don’t want to push it too much - the consent issue- because I’m conscious that you have (for good reasons) withheld some details.
But purely on the basis of the information you’ve given, I think there has got to be a big question mark over whether this girl was sober enough to consent to sex. She’d been drinking, to such an extent that she’d passed out shortly before, while waiting to be collected. That sounds to me like being too drunk for meaningful consent. The fact that she’d slept with this man previously doesn’t affect this - you need to consent each time. Nor does the fact that she is older & had been in the armed services. Anyone can be raped when drunk. Sadly.
There’s such a huge stigma attached to rape & sexual assault - it can be very difficult to face up to the possibility of it happening in your own life, particularly when the possible victim is seen as a ‘bad girl’- drunk, promiscuous, a disloyal friend.
Someone above mentioned that the consent question wasn’t your issue. I see the point - but I think it needs to be. One point is that younger women can be very vulnerable to male exploitation - I think we (older women) with more life experience need to step up to protect them. It is a moral duty, however unlikeable they may be. The other is that your daughter is with this guy. If he raped this girl, if he was careless about consent, if he took advantage of a drunk young woman, that’s a huge issue for your daughter (even putting aside his absolutely appalling behaviour in having sex with her in the same room). Not just in terms of your her well being - how will he treat her? - but also in terms of why she doesn’t see this is a problem. How does she see relationships? Why? Is she vulnerable to predatory men?
There’s a film (documentary) on Netflix called Audrie and Daisy. Might be worth watching with your daughter before uni to lead onto a discussion of male behaviour, alcohol & sex. (It’s extremely sad. Daisy committed suicide very recently.)
But in your shoes, on the info you’ve given, I would be trying to speak to someone in my local force who deals with sexual offences, to ask for advice. I’d just want to know I’d tried.
Sorry for the essay.