Being left behind is read as a deep fear of being alone when it matters most. Dream books connect abandonment to early attachments and to a wish to be reassured of staying remembered and held in mind.
Has this come up in your dreams before? What was going on in your life then?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.