Frankly, he throws tantrums and acts like a baby because he can. You engage him, you allow the bad behavior and (I suspect) you often give in to it.
I suggest that the next time he does it that you tell him something like this:
“Look XYZ, I love you and I’ve told you where I am going and what I am going to be doing. As much as I adore you I am sick and tired of these tempter tantrums over nothing and I am not going to engage in this behavior any more. If you want to pout and sleep on the couch, pout and sleep on the couch. If you want to be silent and act like a spoiled brat who isn’t getting their way — be silent and act like a spoiled brat. However, please understand that I want to be in a relationship with a man — not a child. I am not going to acknowledge or engage you when you are displaying this childish behavior any longer.”
Then don’t. Don’t acknowledge or engage him. Don’t say one more word about it. Nothing. Go about doing what you told him that you were going to do and let him have the tantrum on his own.
If you ignore the bad behavior — and I mean completely — I strongly suspect it will stop.
