The only reason marriages lasted longer back in the day was because women were essentially indirectly forced to be with men. The whole bank account thing in the US is a really good example of how screwed women were. There were a lot of very long marriages that were deeply unhappy.

Nowadays, women get at least some amount of freedom to choose their partners and hundreds/thousands of years of men not having to actually be good people has meant that many of us are lonely and blame the women for having some standards. Good communication and mutual respect go a long way and those are the marriages that last these days.