Do not assume that someone who has been nonviolent in the past will be nonviolent in the future. Before you find yourself alone with a date, clarify your intentions with each other. Behaving passively or submissively can foster that myth. Always be direct and assertive in all communications throughout an evening, from what you choose to eat at dinner to what you are interested in sexually. Be verbally assertive.
Assertive responses are direct, honest, appropriate and spontaneous.
Speak in a calm, controlled manner while looking directly at the harasser. I want you to stop now. Be physically assertive. Look confident and competent. It's important that your words and actions be consistent.