GIRLFRIEND WANTS ANAL SEX
That said, many STDs are asymptomatic, and a person can even be a carrier of an STD and spread it to others without knowing it. You can't tell a person is "clean" just by looking - a recent series of STD tests or knowledge that your partner hasn't had any other sex partners is necessary to be sure that they are free of STDs.
It's important to talk with your partner about what it means to have sex without a condom, particularly anal sex, which is a more risky activity for spreading STDs and HIV than vaginal intercourse. It won't be an easy conversation, but it's better to have it now than to worry later. You can cover subjects like being exclusive, trust, drawing the lines for safer sex, STD testing and more. A few tips for the talk:
To your health,
STD TRANSMISSION AND PREVENTION ADVICE
Latex, polyurethane, male, female -- we've got the lowdown on them all.