Excitedly captioned, "It's happening! I'm going to be a dad," the photo pretty much assures fans that their relationship is doing alright.
This will be the first child for both Sean, 32, and Catherine, 29.
#ICYMI: Catherine beat out 26 women for Sean's love on national television - including The Bachelorette's Emily Maynard, who eliminated him in that season's penultimate episode. They were married, again on national television, in January 2014.