I wasn't here for the referendum in question, but it is pretty clear from what I've read about it that there was a completely different dynamic at work in that debate compared to the abortion debate. For starters, a year before the referendum, polls were showing the public as split down the middle over whether the ban on divorce should be removed. Yet when it actually went to a vote, the ban was overwhelmingly reaffirmed (something like 68% to 32% IIRC). Assuming the original polls were accurate at the time, that seems to me to indicate that you had a lot of people not ideologically (or religiously) opposed to divorce who were nevertheless swayed by some other argument that the status quo should be maintained. I just don't think you get ideological/religious shifts of that magnitude in such a short space of time. So clearly, it wasn't just moral opposition to divorce, per se, that defeated the first referendum.
A co-worker of mine who was active in the campaign to change the law reckons a lot of it was pure cynicism on the part of Fianna Fáil, the "dominant party" referred to in that review. They were in opposition at the time and he thinks they calculated that it was more to their benefit to take the No side and they just threw in any argument they could come up with.