I find that the best way is to get the "strop" out of the way and then laugh about the situation later.
Had one the other lunch time. Went to find my fella to say i'd meet him at home for lunch, and he said he would be half an hour....I flipped and said, "what did he think I would do...Wait around for half an hour for him to get his butt in gear?" after stomping off, he came and found me and I just gave him a puppy dog look and we just giggled!
Laughter is a great cure for anything like that. It's a stage that is all part of being pregnant, and although at the time I thought he was being difficult on purpose, I didn't want it to drag on.....He was definately wrong though! Lol