Wow... Im so sorry to hear about your friend. I hope she is ok.
I dont have alot of insight but I can tell you what happened when I set boundries with my ex-ABF... He disapeared.
Honestly I think they know what they are doing is not right for them. Even though my ex does not drink (sober 6 months) he is now addicted to his recovery. I say that because he is not really changing his irresponsible behavior, he still is not paying his bills, taking care of the basics in his life nor is he getting counceling for the deep seeded issues. It is easier for him, (in the name of recovery) Not to be around me because when he is around me he feels guilt, or judged. As hard as I have tried, I cant sit back and say nothing... so I set boundries.... He does not talk to me anymore.
I do love this person, but I cant want more for him then he wants for himself. So if he calls I will try to be supportive, but I will not do anything to "fix" his issues. Sometimes the hardest thing to do is the only thing you can do.... Let Go. If they want help and are really looking they will come back to the people that loved them enough to be honest.