New here looking for REAL help

im a 30 y/o guy that wants to watch my gf fuck other men. Im as real and serious about this as possible. I have told her i wanted it so she is not clueless. I need help on how to convince her or any other idea. Ill do whatever it takes. After i told her she got real turned on by it for couple months, we talked bout it during sex, masturbated to it, even bought her a larger dildo she loves... the out of no where she said it wasnt her totally backed off... help please!