No it's not legitimate and he shouldn't expect you to just go home and be alone if all you were doing was going to Walmart then his getting mad is a little absurd at least you weren't going to a bar and a dance club you were just going shopping. He has to learn to trust you at some point since you will be husband and wife someday. He has to learn to respect you as your own person is you mold yourself around him you will only lose yourself in the process. Many women when they get into a relationship or a marriage make their mate their all and then when things don't work out they no longer know who they are anymore and then they have to find themselves all over again.
You have to have your own space and time to yourself and you need to tell him that in no uncertain terms. He is going to have to stop getting angry when you don't do as he wants you to do and as long as you stand your ground he will realize that you aren't doing anything you shouldn't be doing.