It happens to us too. I always make sure to say goodbye to my son... see you in a bit or something that will bring the memory of me returnong after. My husband also engage him in somr type of conversation... and overall we try to look as if it isn't a big deal.
Good luck!!

Turn on music- give him a toy to fiddle with. Message his legs and feet talk to him in a calm tone through his crying.. and let him self sooth it is a part of development, the separation anxiety.

sensory Mitt that is on my site may help.

We have run into this as well - Lukas has a tantrum when my wife gets out of the car, but not when I do - and pretty much pinpointed it to the fact that in almost every instance of Lukas getting into a car with my wife driving, he gets out of the car when she does. (Oftentimes my wife will drop me off at work, so it's normal in his mind for Dad to leave.) So if I'm driving and she gets out of the car, he treats this as a break in the routine and has a tantrum until she comes back.

After all this, I confess I don't have an answer, but identifying the trigger for us was half the battle, and wonder if the issue is the same for your child. If you find a solution that works, PLEASE keep me in the loop - this is a sticky challenge!

I don't know. But, I can relate my son is going on 4 and he crys when I walk away, such as work or to the store. Sometimes he runs after me. I feel so bad when he feels that way. I keep him so close and protected. He takes it hard when we separate. I wonder also what can I do for him to make him feel safe for the moment until I return.