What can a friend do

I've got a question,
this is just my perspective looking in form the side line.....

One of my best frnds is in a relationship that is going no where. The guy she is involved with is a nice guy and respectful. He is sometimes an "iffy" person. When she wants to go out he has issues with that and wants to go out as well. He always wants to be compensated when he buys a meal for her or she needs some money. They live together and are suppose to share equal responsabilities but things dont happen that way. She pays all of the bills and when she asks him for some money he has a problem with it. I think that she is moving out to save money so how can i tell her that this move out should be in her best intrest because he is only bringing her down and stressing her out. you know you can only tell people so much about their relationships I just want to let her know that she can do sooooooooo much better. so let me know what you think on the matter.