I'm a friend of a friend who is about to marry an addict 5 months after meeting him...

TLDR; My 22 year old friend is about to marry a guy in a month after 5 months of knowing him. She told me he has a drug problem, but she says it's not a big deal and she thinks they can work through it. I don't really know any addicts, but this is increasingly alarming to me.

Is there anything I can do to help her wake up? This guy came into her life and quickly asked her to commit to him and told her he's in love with her after like a week and a half. They are both 22 years old. They are actually quite a cute couple, and I can totally see why she likes him, as he's very smart, charming, and seems sincere... But early on, she eluded to "flaws" that he had, and from the way she talked, I suspected he abused drugs almost right away.

It wasn't til bout 6 weeks ago that she confided in me and told me he was abusing prescription methamphetamines. I took it rather seriously - but honestly, I've never actually dated or even been friends with any addicts, so I've not been sure. I met him once or twice in passing, and he was really really quiet, despite her telling me he talks a ton and is very extroverted.

Well, then she tells me a few days ago that he asked her to marry him and she said yes. She didn't really describe the proposal despite me asking, and at first she said he didn't give her a ring, and then the next day she said he actually did.

I got to finally sit down and talk with this guy last night... and I can hardly count how many times he brought up drugs or made some reference to drugs. From weed to alcohol to cocaine to psychedelics. He brought up drugs a lot. At one point, my friend said to him, "This is my best friend. Do you have any questions for her about me?" and he asked, "What is she like on ____" and listed off different drugs, while my friend and I looked at each other awkwardly and replied.. "Uhh.. no, neither of us have done that.." It is clear to me that drugs is on his mind constantly.

So now ALL of my alarms in my head are going off. The wedding is a month from now, even though he JUST asked her to marry him. I asked him why the rush, and he basically said, "why not?" My friend is extremely nervous, but she keeps insisting this is what she wants to do because she loves him.

I know that this is her life and ultimately I can't make her wake up. But is there anything that I can say or do that would help the chances of her realizing how dangerous this is? I don't even think I even fully realize how dangerous this is - and am certain she doesn't either.