Every time you start missing someone you should tell yourself there is a reason they left. If they aren’t coming back there is a very good reason why not. Either they deliberately chose to not have you in their life any longer, or you let them go because of your own insecurities. Whatever the excuse or cause may be, let it be. Let time pass and let things put themselves into perspective. Don’t rush anything, and don’t nag. If something is meant to be… it will be. If it isn’t, life and time will heal you and it will be like it never happened at all.