Unfortunately in the romance department a person has to learn on their own that a relationship is not going to work. It is great that you tried to give her your advice but we really do learn about love through ups and downs such as this. We don't know whether he will come back or not and she will deal with that in due time. You have to let her find her own reasons for every decision regarding this relationship. She will eventually find closure on her own when she is ready. Give her a chance to heal before worrying about another relationship. If she wants to be with him it won't change by replacing it with another relationship. Give her support but let her come to her own conclusions. She will then heal faster. If she isn't dating she may just be trying to get over him. Time heals everything.
I think as a parent I would be less involved with her relationship problems (I see you are trying to tell me it would be best to ignore it), but she calls me often and in the middle of the night crying and crying about it. What do I tell her? I am at a loss....and I have always thought I am a good parent and she could always lean on me...but it just goes on and on.