If you shut yourself off from love, you'll miss out on that woman, and the happiest times of your life.
如果你把自己关在爱的门外,你就会错过这个女子,和你生命中最快乐的时光。
新世纪大学英语综合教程(第2版)第一册
Grey as your first choice means that you want to shut yourself off from everything and remain uncommitted, so that you can swing with opinion and emotions.