Raped but Cant Report It?

My husband and I are polyamorous. My husbands GF and her husband are polyamorous as well. We are all military. Last night my friend/husbands GF was raped by a guy she invited over to her house. She told him nothing sexual and when she passed out she woke up to him kissing her and on top of her. She told him no but he pinned her down and choked her and told her to tell him he could "have it". Finally she gave in because he was literally physically attacking her.

Her husband is deployed right now. She refused to report the man who raped her because in the military you can get in trouble for "adultery" for being in a polyamorous or open relationship. Even if everyone is consenting.

She won't report the rape because she doesn't want her husband to get in trouble.

What should she do?? I don't know what advice to give.