My friend is in a deadend relationship how do I convince her its going nowhere?

My friend is dating a guy from Australia. She is to put in bluntly loud and southern. He is 32 and she 19. Its like watching Wanda Sykes and Hugh Jackman trying to have a relationship she is loud and he is really quite.I think the only thing they have in common is they like sex. She needs more than that, how do I convince her this guy she has met and invited into her home is not going to work out? I seriously wonder what is wrong with girl she is Hawt and needs a hustler, not this fool.