I'm sorry for how I'm about to be mean but this just didn't make sense at. all.
According to the blurb this is about Kat having a pregnancy scare and Carter isn't ready for being a father, like ever. The story is narrated. You'll see Max and Grace and Riley's story is a bit introduced.
And than there's Kat and Carter. A few weeks after their honeymoon she tells him she might be pregnant (they had the talk ealier on their honeymoon, because why discuss it before you get married, and he doesn't want kids.) He goes all Christian 'asshole reaction' Grey and walks out on her after blaming she did it on purpose, while she knew he didn't want kids. The good thing was that eventually she walked away as well. All the way to Chicago (not literally, of course). He realized that he was wrong and he suffered a bit but then, guess what? She isn't pregnant at all! So why are we even reading this? What a waste of time.
After a good talk Kat doesn't go home with Carter so he goes out to celebrate Halloween with his friends. Why...? Then he sees a hot blonde (with curves like Kat). Oh boy, I wonder who that is! She hits on him and he makes it clear that he's married and all but he does think she's hot and blablabla. Eventually he figures out it's Kat. Damn, he can't even reagonize his wife! That was just too stupid. And why even pull off a prank like that in the first place?
And now they lived happily ever after. Until the next novella, perhaps.