You have a delicate situation here. Keep in mind that you need a way to tell her the truth about what she can possibly expect in this kind of relationship once she has tied the knot. If you don’t tell her she could always use you as an excuse for allowing her to go through hell she is about to endure.
You need to educate yourself on various aspects of Islam that directly relate to her.
One is wife beating which is an institution within Islam. How about being confined to the home and never talking to another man unless it is family. How about the consequences of breaking the rules? Honor killing anyone?
How about the status of women in general in Islam? They rank just barely above infidels and we know how Muzzies feel about them. Misogyny within Islam is a given.
How about what happens to the children they have? They are automatically Muslim once they are born because they have a Muzzie father. What if they try and convert out? That act is punishable by death. Does she mind her husband beating and/or possibly killing her children?
Does she mind wearing a burka, chador, or nikab? By doing so she loses her ability to express her individuality to the public.
These are just some of the issues you need to discuss with her. Just let her know that when things go bad enough for her to desire to escape it that you are there to help her get out. Some people need to go to the School of Hard Knocks to really understand certain things.
Then she could write a book afterward about her descent into the living hell of Islam from a Western/American perspective.
There was an article just this week on FR about them not being able to say the name of their mother. Does she want he children to never say her name? How is that love?
Also, she needs to understand to forget about ever having a Christmas tree and presents for the children. Forget about ever going home for family Christmas. No hiding Easter eggs for them at home and having to make her children sit out while classmates have egg hunts. Forget about birthdays for her children. And pray her daughters never get a Valentines card at school from a boy or have a boy lab partner. Forget helping her daughters to pick out a prom dress or sit up waiting for them to come home after a date.