Agree with @elbrant and I'd like to add, when you return be very matter of fact, do not make a big fuss, particularly if she is excited and effusive in her greeting to you. Sure, acknowledge her if you must but don't make any sort of big deal out of it. Go about your business, e.g. if you've been shopping, put your things away before spending any time with her. Your goal is to make your absence just part of a normal routine, nothing to be excited about. I've had two separation anxiety dogs, and you know you have won the battle when the dog just glances at you in an "oh, you're back" way and doesn't bother getting off the couch! Yes, people like it when their dog greets them and makes a big fuss, but if you feed that behaviour you give too much emphasis to your absence and that can grow into anxiety in your dog.
