Let me get this right, you agreed to let him pick the girl and he won't show you the pic or her? I really cant explain why he won't show you the pic. Mabye he wants to surprise you, mabye its someone you know, or mabye its someone he knows you will NOT agree to but he wants and is hoping that if he just shows up with her you will still go through with it. It has been my experience that it is much better and more comforatable for a couple if the girl picks the other woman. Chances are she will be more comforatable with a girl she knows and can trust. This way she is not thinking you picked this girl cuz you like her.