I agree with the posters above that you shouldn’t push religion or inspiration about Yiddishkeit in any way. Just be a positive role model.
13 is very young to be in the situation she’s in, although I guess that’s the world today. You can try to discuss the idea that girls want much more from a relationship that her “boyfriend” is probably looking for. Closeness and true friendship, someone who generally cares about her. Not that she can even understand that so well at her age either. She doesn’t want to be used by someone and then dropped for the next pretty girl who will come along. Try to emphasize that.
A non religious friend, or mother of such a friend might be able to be very helpful too. She is really very young.