How can I reassure my loved one she is not in any danger?

When my dad got scared I used to tell him that I had taken care of everything, that I was always aware of what was going on and that I wasn't going to let anything happen to him. This worked for him.

Does she know what she is scared of? Do you ask her? Is it her safety or something else? Ask her. You may be surprised what you find out. Then reassure her about whatever it is. Nothing may make sense to you. That is when you need to become creative with the therapeutic lies to continue to reassure her. My mom was always afraid something had happened to her little girls. I woukd tell her they were spending the night with friends. And I used names of actual friends that naturally mom liked.