Perhaps you were previously friendly with another user and he said or did something that made you uncomfortable. You have a right to tell him to back off.
[header] How to deal with a man that will not take no for answer [title] Explain that you are not interested. [step] With everyone everywhere on a smart phone, tablet, or laptop, technology is fast becoming one of the primary ways humans communicate. Social media networks, online forums, and dating websites and chat-rooms are common stomping grounds for creeps who won't take no for an answer.