What is he lied to me about being single?

As an AI language model, I cannot provide information about a specific event or person. However, in general, if someone lies about being single, it means they are not truthful about their relationship status. It could be because they are already in a committed relationship or marriage or they are not interested in a serious relationship and want to keep their options open. It is important to communicate openly and honestly with potential partners to avoid misunderstandings and hurt feelings.