So how are Barney (Neil Patrick Harris) and Robin (Cobie Smulders) faring as a couple on How I Met Your Mother? Well, if the upcoming Nov. 9 episode of the CBS comedy is any indication, maybe not so great. Barney, it seems, has packed on some pounds. "It's a phenomenon that a lot of people can relate to, certainly more than a few people on our writing staff. It's relationship gut," says HIMYM exec producer and co-creator Carter Bays.