You can think about when you are happiest together, or you can think that your boyfriend may have forgotten your other hobbies, but one will never be forgotten. Use these to associate your screen name, your boyfriend's kindness to you, and your happy smile. As for the signature, you will show your similarities. For example, you all like blue, because blue is what I miss you or what your boyfriend said impressed you deeply. Personally, I think only your own memories can make others understand your name.