From a woman's perspective?

my wife of twelve years has been talking to this firned of hers that always talks to her in a sexual nature asking her if she gave me the good lovin or something along those lines. he keeps bringing up sex and things in my opinion you shouldn't. i tell her it bothers me and he's flirting she says i'm being overbearing and controlling and i can;t tell herwho to be friends with, but i tell her he wouldn't bring up sex unless he;s interrested, since i;m a guy and i know. she says he's not, but in my opinion she can't be that naive. what would you do, i;ve talked to her but that didin;t work and they still talk, he even calls her at work.