DEAR HARRIETTE: I have never had a significant other in my life, and I am starting to feel behind because it seems everyone around me is in a relationship. I know that everyone has their own journey, but as I grow older — I'm 19 now — I want to start having relationships to see what I want in a significant other. I don't want to be in my mid-to-late 20s when I begin dating, but it feels so difficu…