In a former post, I wrongly accused Pope Gregory II (715-731), Pope Eugene II (824-827) and Pope Leo IV (847-855) of allowing divorce and remarriage in Rome. Here, Pope Gregory appears to advocate it:
Gregory II, "On Divorce and Remarriage": As regards your question what a husband is to do, if his wife has been attacked by illness, so that she is incapable of conjugal intercourse, it were best if he could continue as he is and practice self-restraint. But since this demands exceptional virtue, the man who cannot live in continence, had better marry. But let him not fail to furnish her with support, since she is kept from married life by sickness, not debarred from it by some abominable offence.
But in the apostate Cardinal Robert Bellarmine's On the Roman Pontiff, Vol. 2, Bk 4, #12, he explains that Pope Gregory made an error, but it was not in allowing divorce and remarriage:
Apostate Bellarmine, On the Roman Pontiff, IV, 12: It cannot be said that this error of Gregory is manifest heresy against the Gospel. For Gregory did not teach that a wife might be divorced and another married; which is expressly against the Gospel and the law of nature; but he taught that in a certain case, with permission of the wife, a man might marry a second wife, so as to have two wives, as Abraham did. Which is indeed false, and is so defined in the Council of Trent, Sess. 24, can. 2. But it does not seem then to have been an ascertained error…
Canon 36: No man may leave his acknowledged wife, except for the cause of fornication, and then marry another: otherwise it behooves the transgressor to be joined to the first marriage.
This canon says the opposite, that if a man has left his wife for any reason except fornication, he must return to her, even if he has contracted another marriage. It does not say that a man can marry again if his wife is unfaithful.
This being cleared up, it should nevertheless be pointed out that such an error as promoting Old Testament bigamy, does nothing in support of the idea of papal infallibility! On the contrary, it shows a grave error in judgment, as well as an early attempt to find theological loopholes, a feat which the later scholastics of the west perfected. In fact, the western "development of dogma" has reached such an absurd point today, that long-standing marriages can now be "annulled" on the grounds of "psychological immaturity". This, of course, is nonsense! Everyone is immature when they get married. Holy Matrimony is supposed to give them the grace to grow up!