V'Las' administration may have been corrupt and secretly run by Romulans, but perhaps womens' rights were better in this era. Thus T'Pol having the freedom to divorce Koss. When T'Pau and her group took over in Enterprise, they may have reverted womens' rights to a more restrictive culture.
The only reason we're really given that T'Pau and her Surak religious fanatic group in Enterprise is good is because V'Las' group is run by human hating Romulans that are even worse. In Amok Time we see the full consequences of Archer throwing in with this group, the lesser evil so to speak, meaning that T'Pring's rights are far more restrictive than T'Pol's were a century ago.
That is certainly possible and is consistent with canon, but I wouldn't go with that explanation just yet. I can imagine the nascent Federation accepting that some of its founding Member States have rare archaic rituals that violate basic UFP principles if those rituals are rare and almost never invoked, but I have trouble imagining the Federation allowing one of its Member States to allow women's rights to actively get worse without intervening and forcing them to either stop it or be ejected from the UFP.