Presenting the facts to dad-to-be with a twinkle in your eye might make life a bit easier for both of you.
Put it to him like this:
Imagine you feel sick. Not for a single moment but 24/7. Remember the worst hang-over you ever had in your life or the last time you had an awful stomach bug. You are throwing up and eating seems like torture. And on top of all that, everybody looks at you like you are one of the seven wonders of the world. They expect you to function like normal, go to work and beam with happiness all the time. So, what can you do to ease my nightmare?
His ideal reaction:
Show a bit of understanding. In fact, show a lot of understanding. Especially for your crazy food cravings and other wishes that may seem like bananas. When you have extreme mood swings, including unfair words or passionate outbreaks, I'll tell you how brave and beautiful you are.