Don't go to craigslist.
Your girlfriend is a dope sweetheart. You should find somebody else to bring out her Evil Angel. Find a gal with a different body type. Large, natural breast on one, and a flat rack on the other, is very good for role play.
This will bring out whatever hidden fantasies she has. Ask her to shave her pubic hair. This will make her feel very,very oversexed.
Get her in an absurd costume. Then when she takes it off, cover her body with baby oil. Her skin will feel, to her, like it is heating up. And it will be difficult for her to resist allowing to people all over her.
Give her 10mg of Adderall. The Teva generic makes me really horny. And when I cum, there is this burning sensation in my dick that feels ten times better that a sober orgasm.
Also, do you smoke tobacco? When I take Adderall, and I smoke a cigarette, I get really horny. and when you have problems with vasoconstriction and you can't get it up, it helps. Get a hookah.
This is the grand, cosmic joke of amphetamines on the human race. It makes you really horny, and it next to impossible to maintain an erection and cum.