DEAR AMY: I am a single woman in my mid-50s. I never married or had children and like it this way. I enjoy people, but am a classic introvert who recuperates her energy by being alone. I enjoy going to museums and restaurants on my own. There is a restaurant/bar right down the street from me that I enjoy going to. Recently, I went to this restaurant by myself and sat at the bar to have a drink and maybe eat something. I wasn’t there for long when a man came up beside me, saddled up, and took up conversation with me. I really didn’t want to talk to him, and I didn’t want him sitting next to me….