The message is clear: NEVER GET INVOLVED WITH A MAN WHO HAS A FEMALE "BEST FRIEND!" They are already a couple and have been for years. Eventually they are going to be "friends with benefits" so any other woman is just the outsider and always will be. The ML is a mommy's boy and just likes having as many women around him taking care of his needs as possible. He would never mature and set healthy boundaries, because he doesn't have to. The FL already had plenty of evidence that his "best friend" would never stop coming between them. Too bad she was optimistic enough to get engaged!