My girl actually loves it. Our first time I didn't even have to talk her into it. She asked me if I wanted to try because about a week earlier we were watching some porn and the girl was getting off big time while getting it and she was interested. So that would be best. Implant the idea in her head, wait a bit while it resonates, then if you must, ask if she wants to try.
She now wants it at least once a month.