It was MUCH harder than couples matching into residency honestly. I think that's why we feel a bit blindsided. We had 16 interviews that matched up (same institution). When interviews came out, if one of us had an IV and the other didn't, we would reach out. This was incredibly successful. However, our top ~7 were (in hindsight) places that initially, only one of us had gotten an interview, so I think that hurt us. Also, neither of us has an impressive research background. Fellows couples matches are also much less common, so programs will either not notice that you're a couple or not make much of an effort to speak to the other department (at least that was my impression).
I think we made the mistake of underestimating the competitiveness of our respective specialties and the fact that a GI-Cards couples match would be another level of difficult. We did it for IM 3 years ago and matched at our #1, so naively thought it would be like that this time. Other couples at our program the past 5 years had a similar experience. I guess my advice would be...if you decide to couples match into fellowship, understand that you will almost certainly be sacrificing something to succeed, perhaps in a much more notable way than with a residency match. We matched at a legitimately great program - just lower on our list because of geography.
That said, I'd do it all over again to make sure I'm not living apart from my spouse.