I believe this is a guy that grooms his victims before striking. What I mean is he sets up dates with them a couple of times and gets to know everything about them, i.e. drug addict, affilated with pimp, etc and then decided if the girl is a right victim. That is why the girls felt comfortable and left without their phones. I also believe he offers more and more money, or gifts after each date, and has them loose their gurad more and more. For example, on the second date he might say "you come to me this time," and on third date he might say "you come to me without phone." I also believe he maybe former law enforcement and lets the girls know this, and also gives them tips on how to not get caught escorting, etc. This way they trust him even that much more. Finally, he also makes it known that he doesnt want his reputation to be ruined and tells the girls to never mention anything to anyone about him. This is why I think Amber didnt tell her boyfriend/pimp the guys name or give any details, and just said "thats not what he wants" before leaving.